| r0.1 | label_boi_a2/Households | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| r0.2 | label_boi_a2/Of which: housing loans | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| r0.3 | label_boi_a2/Of which: credit cards | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| r0.4 | label_boi_a2/Private banking | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| r0.5 | label_boi_a2/Micro and small business | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| r0.6 | label_boi_a2/Medium business | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| r0.7 | label_boi_a2/Large business | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| r0.8 | label_boi_a2/Institutional | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| r0.9 | label_boi_a2/Financial management | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| r0.10 | label_boi_a2/Other segmen | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| r0.11 | label_boi_a2/Total Domestic activity | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r0.12 | label_boi_a2/Total activity abroad | | | | N/A | N/A | boi_CS:x2 | boi_GA:x2 | N/A | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r0.13 | label_boi_a2/Total | | | | N/A | N/A | boi_CS:x2 | N/A | N/A | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 1.1 | Interest income from outside segment/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.2 | Interest income from outside segment/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | boi_SE:x44 | N/A | N/A |
| 1.3 | Interest income from outside segment/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | boi_SE:x44 | N/A | N/A |
| 1.4 | Interest income from outside segment/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.5 | Interest income from outside segment/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.6 | Interest income from outside segment/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.7 | Interest income from outside segment/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.8 | Interest income from outside segment/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.9 | Interest income from outside segment/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.10 | Interest income from outside segment/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.11 | Interest income from outside segment/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.12 | Interest income from outside segment/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 1.13 | Interest income from outside segment/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.1 | Interest expenditure to outside segment/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.2 | Interest expenditure to outside segment/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | boi_SE:x44 | N/A | N/A |
| 2.3 | Interest expenditure to outside segment/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | boi_SE:x44 | N/A | N/A |
| 2.4 | Interest expenditure to outside segment/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.5 | Interest expenditure to outside segment/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.6 | Interest expenditure to outside segment/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.7 | Interest expenditure to outside segment/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.8 | Interest expenditure to outside segment/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.9 | Interest expenditure to outside segment/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.10 | Interest expenditure to outside segment/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.11 | Interest expenditure to outside segment/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.12 | Interest expenditure to outside segment/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 2.13 | Interest expenditure to outside segment/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| r3.1 | Interest income, net:/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| r3.2 | Interest income, net:/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| r3.3 | Interest income, net:/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| r3.4 | Interest income, net:/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| r3.5 | Interest income, net:/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| r3.6 | Interest income, net:/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| r3.7 | Interest income, net:/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| r3.8 | Interest income, net:/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| r3.9 | Interest income, net:/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| r3.10 | Interest income, net:/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| r3.11 | Interest income, net:/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r3.12 | Interest income, net:/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r3.13 | Interest income, net:/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 3.1 | From outside segment/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.2 | From outside segment/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | boi_SE:x44 | N/A | N/A |
| 3.3 | From outside segment/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | boi_SE:x44 | N/A | N/A |
| 3.4 | From outside segment/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.5 | From outside segment/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.6 | From outside segment/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.7 | From outside segment/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.8 | From outside segment/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.9 | From outside segment/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.10 | From outside segment/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.11 | From outside segment/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.12 | From outside segment/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 3.13 | From outside segment/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 4.1 | From within segment/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.2 | From within segment/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | boi_SE:x45 | N/A | N/A |
| 4.3 | From within segment/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | boi_SE:x45 | N/A | N/A |
| 4.4 | From within segment/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.5 | From within segment/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.6 | From within segment/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.7 | From within segment/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.8 | From within segment/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.9 | From within segment/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.10 | From within segment/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.11 | From within segment/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.12 | From within segment/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 4.13 | From within segment/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 5.1 | Total interest income, net/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 5.2 | Total interest income, net/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 5.3 | Total interest income, net/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 5.4 | Total interest income, net/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 5.5 | Total interest income, net/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 5.6 | Total interest income, net/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 5.7 | Total interest income, net/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 5.8 | Total interest income, net/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 5.9 | Total interest income, net/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 5.10 | Total interest income, net/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 5.11 | Total interest income, net/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 5.12 | Total interest income, net/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 5.13 | Total interest income, net/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r7.1 | Non-interest income/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| r7.2 | Non-interest income/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| r7.3 | Non-interest income/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| r7.4 | Non-interest income/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| r7.5 | Non-interest income/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| r7.6 | Non-interest income/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| r7.7 | Non-interest income/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| r7.8 | Non-interest income/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| r7.9 | Non-interest income/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| r7.10 | Non-interest income/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| r7.11 | Non-interest income/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r7.12 | Non-interest income/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r7.13 | Non-interest income/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | N/A | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 6.1 | From outside segment/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.2 | From outside segment/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | boi_SE:x44 | N/A | N/A |
| 6.3 | From outside segment/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | boi_SE:x44 | N/A | N/A |
| 6.4 | From outside segment/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.5 | From outside segment/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.6 | From outside segment/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.7 | From outside segment/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.8 | From outside segment/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.9 | From outside segment/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.10 | From outside segment/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.11 | From outside segment/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.12 | From outside segment/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 6.13 | From outside segment/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | N/A | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 7.1 | From within segment/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.2 | From within segment/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | boi_SE:x45 | N/A | N/A |
| 7.3 | From within segment/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | boi_SE:x45 | N/A | N/A |
| 7.4 | From within segment/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.5 | From within segment/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.6 | From within segment/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.7 | From within segment/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.8 | From within segment/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.9 | From within segment/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.10 | From within segment/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.11 | From within segment/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.12 | From within segment/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 7.13 | From within segment/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | N/A | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 8.1 | Total non-interest income/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 8.2 | Total non-interest income/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 8.3 | Total non-interest income/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 8.4 | Total non-interest income/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 8.5 | Total non-interest income/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 8.6 | Total non-interest income/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 8.7 | Total non-interest income/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 8.8 | Total non-interest income/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 8.9 | Total non-interest income/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 8.10 | Total non-interest income/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 8.11 | Total non-interest income/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 8.12 | Total non-interest income/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 8.13 | Total non-interest income/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | N/A | boi_MC:x127 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 9.1 | Total income/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 9.2 | Total income/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 9.3 | Total income/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 9.4 | Total income/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 9.5 | Total income/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 9.6 | Total income/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 9.7 | Total income/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 9.8 | Total income/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 9.9 | Total income/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 9.10 | Total income/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 9.11 | Total income/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 9.12 | Total income/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 9.13 | Total income/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x455 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 10.1 | Credit-loss expenditure/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 10.2 | Credit-loss expenditure/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 10.3 | Credit-loss expenditure/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 10.4 | Credit-loss expenditure/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 10.5 | Credit-loss expenditure/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 10.6 | Credit-loss expenditure/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 10.7 | Credit-loss expenditure/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 10.8 | Credit-loss expenditure/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 10.9 | Credit-loss expenditure/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 10.10 | Credit-loss expenditure/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 10.11 | Credit-loss expenditure/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 10.12 | Credit-loss expenditure/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 10.13 | Credit-loss expenditure/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | N/A | boi_MC:x126 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r13.1 | Operating and other expenses/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| r13.2 | Operating and other expenses/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| r13.3 | Operating and other expenses/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| r13.4 | Operating and other expenses/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| r13.5 | Operating and other expenses/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| r13.6 | Operating and other expenses/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| r13.7 | Operating and other expenses/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| r13.8 | Operating and other expenses/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| r13.9 | Operating and other expenses/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| r13.10 | Operating and other expenses/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| r13.11 | Operating and other expenses/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r13.12 | Operating and other expenses/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r13.13 | Operating and other expenses/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | N/A | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 11.1 | To outside segment/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.2 | To outside segment/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | boi_SE:x44 | N/A | N/A |
| 11.3 | To outside segment/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | boi_SE:x44 | N/A | N/A |
| 11.4 | To outside segment/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.5 | To outside segment/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.6 | To outside segment/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.7 | To outside segment/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.8 | To outside segment/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.9 | To outside segment/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.10 | To outside segment/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.11 | To outside segment/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.12 | To outside segment/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 11.13 | To outside segment/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | N/A | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x44 | N/A | N/A |
| 12.1 | To within segment/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.2 | To within segment/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | boi_SE:x45 | N/A | N/A |
| 12.3 | To within segment/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | boi_SE:x45 | N/A | N/A |
| 12.4 | To within segment/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.5 | To within segment/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.6 | To within segment/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.7 | To within segment/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.8 | To within segment/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.9 | To within segment/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.10 | To within segment/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.11 | To within segment/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.12 | To within segment/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 12.13 | To within segment/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | N/A | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | boi_SE:x45 | N/A | N/A |
| 13.1 | Total operating and other expenses/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 13.2 | Total operating and other expenses/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 13.3 | Total operating and other expenses/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 13.4 | Total operating and other expenses/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 13.5 | Total operating and other expenses/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 13.6 | Total operating and other expenses/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 13.7 | Total operating and other expenses/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 13.8 | Total operating and other expenses/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 13.9 | Total operating and other expenses/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 13.10 | Total operating and other expenses/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 13.11 | Total operating and other expenses/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 13.12 | Total operating and other expenses/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 13.13 | Total operating and other expenses/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | N/A | boi_MC:x160 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 14.1 | Pre-tax profit/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 14.2 | Pre-tax profit/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 14.3 | Pre-tax profit/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 14.4 | Pre-tax profit/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 14.5 | Pre-tax profit/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 14.6 | Pre-tax profit/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 14.7 | Pre-tax profit/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 14.8 | Pre-tax profit/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 14.9 | Pre-tax profit/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 14.10 | Pre-tax profit/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 14.11 | Pre-tax profit/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 14.12 | Pre-tax profit/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 14.13 | Pre-tax profit/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x123 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 15.1 | Provision for taxes on profit/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 15.2 | Provision for taxes on profit/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 15.3 | Provision for taxes on profit/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 15.4 | Provision for taxes on profit/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 15.5 | Provision for taxes on profit/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 15.6 | Provision for taxes on profit/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 15.7 | Provision for taxes on profit/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 15.8 | Provision for taxes on profit/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 15.9 | Provision for taxes on profit/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 15.10 | Provision for taxes on profit/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 15.11 | Provision for taxes on profit/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 15.12 | Provision for taxes on profit/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 15.13 | Provision for taxes on profit/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | N/A | boi_MC:x190 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 16.1 | Post-tax profit/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 16.2 | Post-tax profit/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 16.3 | Post-tax profit/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 16.4 | Post-tax profit/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 16.5 | Post-tax profit/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 16.6 | Post-tax profit/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 16.7 | Post-tax profit/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 16.8 | Post-tax profit/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 16.9 | Post-tax profit/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 16.10 | Post-tax profit/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 16.11 | Post-tax profit/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 16.12 | Post-tax profit/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 16.13 | Post-tax profit/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x122 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 17.1 | Share of banking corp. in profits of included companies/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 17.2 | Share of banking corp. in profits of included companies/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 17.3 | Share of banking corp. in profits of included companies/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 17.4 | Share of banking corp. in profits of included companies/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 17.5 | Share of banking corp. in profits of included companies/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 17.6 | Share of banking corp. in profits of included companies/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 17.7 | Share of banking corp. in profits of included companies/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 17.8 | Share of banking corp. in profits of included companies/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 17.9 | Share of banking corp. in profits of included companies/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 17.10 | Share of banking corp. in profits of included companies/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 17.11 | Share of banking corp. in profits of included companies/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 17.12 | Share of banking corp. in profits of included companies/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 17.13 | Share of banking corp. in profits of included companies/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x191 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r21.1 | Net profit/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| r21.2 | Net profit/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| r21.3 | Net profit/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| r21.4 | Net profit/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| r21.5 | Net profit/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| r21.6 | Net profit/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| r21.7 | Net profit/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| r21.8 | Net profit/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| r21.9 | Net profit/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| r21.10 | Net profit/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| r21.11 | Net profit/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r21.12 | Net profit/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r21.13 | Net profit/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 18.1 | Before attribution to holders of rights that do not confer control/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 18.2 | Before attribution to holders of rights that do not confer control/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 18.3 | Before attribution to holders of rights that do not confer control/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 18.4 | Before attribution to holders of rights that do not confer control/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 18.5 | Before attribution to holders of rights that do not confer control/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 18.6 | Before attribution to holders of rights that do not confer control/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 18.7 | Before attribution to holders of rights that do not confer control/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 18.8 | Before attribution to holders of rights that do not confer control/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 18.9 | Before attribution to holders of rights that do not confer control/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 18.10 | Before attribution to holders of rights that do not confer control/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 18.11 | Before attribution to holders of rights that do not confer control/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 18.12 | Before attribution to holders of rights that do not confer control/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 18.13 | Before attribution to holders of rights that do not confer control/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 19.1 | Attributed to holders of rights that do not confer control/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 19.2 | Attributed to holders of rights that do not confer control/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 19.3 | Attributed to holders of rights that do not confer control/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 19.4 | Attributed to holders of rights that do not confer control/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 19.5 | Attributed to holders of rights that do not confer control/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 19.6 | Attributed to holders of rights that do not confer control/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 19.7 | Attributed to holders of rights that do not confer control/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 19.8 | Attributed to holders of rights that do not confer control/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 19.9 | Attributed to holders of rights that do not confer control/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 19.10 | Attributed to holders of rights that do not confer control/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 19.11 | Attributed to holders of rights that do not confer control/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 19.12 | Attributed to holders of rights that do not confer control/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_GA:x2 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 19.13 | Attributed to holders of rights that do not confer control/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | N/A | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 20.1 | Attributed to shareholders in banking corp./Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 20.2 | Attributed to shareholders in banking corp./Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 20.3 | Attributed to shareholders in banking corp./Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 20.4 | Attributed to shareholders in banking corp./Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 20.5 | Attributed to shareholders in banking corp./Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 20.6 | Attributed to shareholders in banking corp./Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 20.7 | Attributed to shareholders in banking corp./Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 20.8 | Attributed to shareholders in banking corp./Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 20.9 | Attributed to shareholders in banking corp./Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 20.10 | Attributed to shareholders in banking corp./Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 20.11 | Attributed to shareholders in banking corp./Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x1 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 20.12 | Attributed to shareholders in banking corp./Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_GA:x2 | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 20.13 | Attributed to shareholders in banking corp./Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | N/A | boi_MC:x121 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 21.1 | Avg. asset balance/Households | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 21.2 | Avg. asset balance/Of which: housing loans | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 21.3 | Avg. asset balance/Of which: credit cards | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 21.4 | Avg. asset balance/Private banking | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 21.5 | Avg. asset balance/Micro and small business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 21.6 | Avg. asset balance/Medium business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 21.7 | Avg. asset balance/Large business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 21.8 | Avg. asset balance/Institutional | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 21.9 | Avg. asset balance/Financial management | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 21.10 | Avg. asset balance/Other segmen | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 21.11 | Avg. asset balance/Total Domestic activity | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 21.12 | Avg. asset balance/Total activity abroad | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 21.13 | Avg. asset balance/Total | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_MC:x1 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 22.1 | Of which: Investments in included companies1/Households | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 22.2 | Of which: Investments in included companies1/Of which: housing loans | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 22.3 | Of which: Investments in included companies1/Of which: credit cards | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 22.4 | Of which: Investments in included companies1/Private banking | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 22.5 | Of which: Investments in included companies1/Micro and small business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 22.6 | Of which: Investments in included companies1/Medium business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 22.7 | Of which: Investments in included companies1/Large business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 22.8 | Of which: Investments in included companies1/Institutional | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 22.9 | Of which: Investments in included companies1/Financial management | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 22.10 | Of which: Investments in included companies1/Other segmen | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 22.11 | Of which: Investments in included companies1/Total Domestic activity | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 22.12 | Of which: Investments in included companies1/Total activity abroad | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 22.13 | Of which: Investments in included companies1/Total | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_MC:x54 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 23.1 | Of which: Avg. balance of credit to public1/Households | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.2 | Of which: Avg. balance of credit to public1/Of which: housing loans | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | boi_SE:x319 | N/A | N/A | N/A |
| 23.3 | Of which: Avg. balance of credit to public1/Of which: credit cards | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | boi_SE:x302 | N/A | N/A | N/A |
| 23.4 | Of which: Avg. balance of credit to public1/Private banking | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.5 | Of which: Avg. balance of credit to public1/Micro and small business | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.6 | Of which: Avg. balance of credit to public1/Medium business | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.7 | Of which: Avg. balance of credit to public1/Large business | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.8 | Of which: Avg. balance of credit to public1/Institutional | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.9 | Of which: Avg. balance of credit to public1/Financial management | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.10 | Of which: Avg. balance of credit to public1/Other segmen | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.11 | Of which: Avg. balance of credit to public1/Total Domestic activity | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.12 | Of which: Avg. balance of credit to public1/Total activity abroad | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 23.13 | Of which: Avg. balance of credit to public1/Total | boi_met:md1065 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_MC:x8 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.1 | Outstanding credit to public at end of reporting period/Households | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.2 | Outstanding credit to public at end of reporting period/Of which: housing loans | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | boi_SE:x319 | N/A | N/A | N/A |
| 24.3 | Outstanding credit to public at end of reporting period/Of which: credit cards | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | boi_SE:x302 | N/A | N/A | N/A |
| 24.4 | Outstanding credit to public at end of reporting period/Private banking | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x330 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.5 | Outstanding credit to public at end of reporting period/Micro and small business | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x313 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.6 | Outstanding credit to public at end of reporting period/Medium business | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x310 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.7 | Outstanding credit to public at end of reporting period/Large business | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x309 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.8 | Outstanding credit to public at end of reporting period/Institutional | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x308 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.9 | Outstanding credit to public at end of reporting period/Financial management | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x304 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.10 | Outstanding credit to public at end of reporting period/Other segmen | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x324 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.11 | Outstanding credit to public at end of reporting period/Total Domestic activity | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.12 | Outstanding credit to public at end of reporting period/Total activity abroad | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 24.13 | Outstanding credit to public at end of reporting period/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 25.1 | Outstanding impaired debts/Households | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.2 | Outstanding impaired debts/Of which: housing loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | boi_ST:x3 | N/A |
| 25.3 | Outstanding impaired debts/Of which: credit cards | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | boi_ST:x3 | N/A |
| 25.4 | Outstanding impaired debts/Private banking | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.5 | Outstanding impaired debts/Micro and small business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.6 | Outstanding impaired debts/Medium business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.7 | Outstanding impaired debts/Large business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.8 | Outstanding impaired debts/Institutional | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.9 | Outstanding impaired debts/Financial management | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.10 | Outstanding impaired debts/Other segmen | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.11 | Outstanding impaired debts/Total Domestic activity | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.12 | Outstanding impaired debts/Total activity abroad | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 25.13 | Outstanding impaired debts/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | boi_ST:x3 | N/A |
| 26.1 | Outstanding debts 90+ days in arrears/Households | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.2 | Outstanding debts 90+ days in arrears/Of which: housing loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.3 | Outstanding debts 90+ days in arrears/Of which: credit cards | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.4 | Outstanding debts 90+ days in arrears/Private banking | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.5 | Outstanding debts 90+ days in arrears/Micro and small business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.6 | Outstanding debts 90+ days in arrears/Medium business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.7 | Outstanding debts 90+ days in arrears/Large business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.8 | Outstanding debts 90+ days in arrears/Institutional | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.9 | Outstanding debts 90+ days in arrears/Financial management | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.10 | Outstanding debts 90+ days in arrears/Other segmen | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.11 | Outstanding debts 90+ days in arrears/Total Domestic activity | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.12 | Outstanding debts 90+ days in arrears/Total activity abroad | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 26.13 | Outstanding debts 90+ days in arrears/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_MC:x8 | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | boi_ST:x3 | boi_TI:x2 |
| 27.1 | Avg. liability balance/Households | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 27.2 | Avg. liability balance/Of which: housing loans | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 27.3 | Avg. liability balance/Of which: credit cards | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 27.4 | Avg. liability balance/Private banking | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 27.5 | Avg. liability balance/Micro and small business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 27.6 | Avg. liability balance/Medium business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 27.7 | Avg. liability balance/Large business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 27.8 | Avg. liability balance/Institutional | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 27.9 | Avg. liability balance/Financial management | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 27.10 | Avg. liability balance/Other segmen | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 27.11 | Avg. liability balance/Total Domestic activity | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 27.12 | Avg. liability balance/Total activity abroad | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 27.13 | Avg. liability balance/Total | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | N/A | boi_MC:x3 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 28.1 | Of which: Avg. balance of deposits of the public1/Households | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.2 | Of which: Avg. balance of deposits of the public1/Of which: housing loans | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | boi_SE:x319 | N/A | N/A | N/A |
| 28.3 | Of which: Avg. balance of deposits of the public1/Of which: credit cards | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | boi_SE:x302 | N/A | N/A | N/A |
| 28.4 | Of which: Avg. balance of deposits of the public1/Private banking | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.5 | Of which: Avg. balance of deposits of the public1/Micro and small business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.6 | Of which: Avg. balance of deposits of the public1/Medium business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.7 | Of which: Avg. balance of deposits of the public1/Large business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.8 | Of which: Avg. balance of deposits of the public1/Institutional | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.9 | Of which: Avg. balance of deposits of the public1/Financial management | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.10 | Of which: Avg. balance of deposits of the public1/Other segmen | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.11 | Of which: Avg. balance of deposits of the public1/Total Domestic activity | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.12 | Of which: Avg. balance of deposits of the public1/Total activity abroad | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 28.13 | Of which: Avg. balance of deposits of the public1/Total | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | N/A | boi_MC:x17 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.1 | Balance of deposits of the public at end of reporting period/Households | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.2 | Balance of deposits of the public at end of reporting period/Of which: housing loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | boi_SE:x319 | N/A | N/A | N/A |
| 29.3 | Balance of deposits of the public at end of reporting period/Of which: credit cards | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x306 | boi_SE:x16 | boi_SE:x302 | N/A | N/A | N/A |
| 29.4 | Balance of deposits of the public at end of reporting period/Private banking | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x330 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.5 | Balance of deposits of the public at end of reporting period/Micro and small business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x313 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.6 | Balance of deposits of the public at end of reporting period/Medium business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x310 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.7 | Balance of deposits of the public at end of reporting period/Large business | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x309 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.8 | Balance of deposits of the public at end of reporting period/Institutional | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x308 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.9 | Balance of deposits of the public at end of reporting period/Financial management | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x304 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.10 | Balance of deposits of the public at end of reporting period/Other segmen | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | boi_SE:x324 | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.11 | Balance of deposits of the public at end of reporting period/Total Domestic activity | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.12 | Balance of deposits of the public at end of reporting period/Total activity abroad | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x17 | N/A | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 29.13 | Balance of deposits of the public at end of reporting period/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | N/A | boi_MC:x17 | N/A | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A | N/A | N/A |
| 30.1 | Avg. balance of risk assets/Households | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 30.2 | Avg. balance of risk assets/Of which: housing loans | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 30.3 | Avg. balance of risk assets/Of which: credit cards | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 30.4 | Avg. balance of risk assets/Private banking | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 30.5 | Avg. balance of risk assets/Micro and small business | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 30.6 | Avg. balance of risk assets/Medium business | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 30.7 | Avg. balance of risk assets/Large business | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 30.8 | Avg. balance of risk assets/Institutional | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 30.9 | Avg. balance of risk assets/Financial management | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 30.10 | Avg. balance of risk assets/Other segmen | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 30.11 | Avg. balance of risk assets/Total Domestic activity | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 30.12 | Avg. balance of risk assets/Total activity abroad | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x2 | N/A | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 30.13 | Avg. balance of risk assets/Total | boi_met:md88 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | N/A | N/A | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 31.1 | Balance of risk assets at end of reporting period/Households | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 31.2 | Balance of risk assets at end of reporting period/Of which: housing loans | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 31.3 | Balance of risk assets at end of reporting period/Of which: credit cards | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 31.4 | Balance of risk assets at end of reporting period/Private banking | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 31.5 | Balance of risk assets at end of reporting period/Micro and small business | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 31.6 | Balance of risk assets at end of reporting period/Medium business | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 31.7 | Balance of risk assets at end of reporting period/Large business | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 31.8 | Balance of risk assets at end of reporting period/Institutional | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 31.9 | Balance of risk assets at end of reporting period/Financial management | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 31.10 | Balance of risk assets at end of reporting period/Other segmen | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 31.11 | Balance of risk assets at end of reporting period/Total Domestic activity | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 31.12 | Balance of risk assets at end of reporting period/Total activity abroad | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | boi_GA:x2 | N/A | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 31.13 | Balance of risk assets at end of reporting period/Total | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | N/A | boi_CS:x2 | N/A | N/A | N/A | N/A | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 32.1 | Avg. balance of assets managed/Households | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 32.2 | Avg. balance of assets managed/Of which: housing loans | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 32.3 | Avg. balance of assets managed/Of which: credit cards | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 32.4 | Avg. balance of assets managed/Private banking | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 32.5 | Avg. balance of assets managed/Micro and small business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 32.6 | Avg. balance of assets managed/Medium business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 32.7 | Avg. balance of assets managed/Large business | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 32.8 | Avg. balance of assets managed/Institutional | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 32.9 | Avg. balance of assets managed/Financial management | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 32.10 | Avg. balance of assets managed/Other segmen | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 32.11 | Avg. balance of assets managed/Total Domestic activity | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 32.12 | Avg. balance of assets managed/Total activity abroad | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 32.13 | Avg. balance of assets managed/Total | boi_met:md1064 | xbrli:monetaryItemType | instant | boi_BC:x29 | N/A | boi_CS:x2 | N/A | boi_MC:x262 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r37.1 | Sources of net interest income:/Households | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| r37.2 | Sources of net interest income:/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| r37.3 | Sources of net interest income:/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| r37.4 | Sources of net interest income:/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| r37.5 | Sources of net interest income:/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| r37.6 | Sources of net interest income:/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| r37.7 | Sources of net interest income:/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| r37.8 | Sources of net interest income:/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| r37.9 | Sources of net interest income:/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| r37.10 | Sources of net interest income:/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| r37.11 | Sources of net interest income:/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r37.12 | Sources of net interest income:/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| r37.13 | Sources of net interest income:/Total | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 33.1 | Profit from credit-issuing activity/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 33.2 | Profit from credit-issuing activity/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 33.3 | Profit from credit-issuing activity/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 33.4 | Profit from credit-issuing activity/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 33.5 | Profit from credit-issuing activity/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 33.6 | Profit from credit-issuing activity/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 33.7 | Profit from credit-issuing activity/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 33.8 | Profit from credit-issuing activity/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 33.9 | Profit from credit-issuing activity/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 33.10 | Profit from credit-issuing activity/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 33.11 | Profit from credit-issuing activity/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 33.12 | Profit from credit-issuing activity/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 33.13 | Profit from credit-issuing activity/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 34.1 | Profit from deposit-acceptance activity/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 34.2 | Profit from deposit-acceptance activity/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 34.3 | Profit from deposit-acceptance activity/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 34.4 | Profit from deposit-acceptance activity/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 34.5 | Profit from deposit-acceptance activity/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 34.6 | Profit from deposit-acceptance activity/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 34.7 | Profit from deposit-acceptance activity/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 34.8 | Profit from deposit-acceptance activity/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 34.9 | Profit from deposit-acceptance activity/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 34.10 | Profit from deposit-acceptance activity/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 34.11 | Profit from deposit-acceptance activity/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 34.12 | Profit from deposit-acceptance activity/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 34.13 | Profit from deposit-acceptance activity/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 35.1 | Other/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 35.2 | Other/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 35.3 | Other/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 35.4 | Other/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 35.5 | Other/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 35.6 | Other/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 35.7 | Other/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 35.8 | Other/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 35.9 | Other/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 35.10 | Other/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 35.11 | Other/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 35.12 | Other/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 35.13 | Other/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | boi_MC:x975 | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 36.1 | Total interest income, net/Households | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | N/A | N/A | N/A | N/A |
| 36.2 | Total interest income, net/Of which: housing loans | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x319 | N/A | N/A | N/A |
| 36.3 | Total interest income, net/Of which: credit cards | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x306 | N/A | boi_SE:x302 | N/A | N/A | N/A |
| 36.4 | Total interest income, net/Private banking | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x330 | N/A | N/A | N/A | N/A | N/A |
| 36.5 | Total interest income, net/Micro and small business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x313 | N/A | N/A | N/A | N/A | N/A |
| 36.6 | Total interest income, net/Medium business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x310 | N/A | N/A | N/A | N/A | N/A |
| 36.7 | Total interest income, net/Large business | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x309 | N/A | N/A | N/A | N/A | N/A |
| 36.8 | Total interest income, net/Institutional | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x308 | N/A | N/A | N/A | N/A | N/A |
| 36.9 | Total interest income, net/Financial management | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x304 | N/A | N/A | N/A | N/A | N/A |
| 36.10 | Total interest income, net/Other segmen | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | boi_SE:x324 | N/A | N/A | N/A | N/A | N/A |
| 36.11 | Total interest income, net/Total Domestic activity | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 36.12 | Total interest income, net/Total activity abroad | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |
| 36.13 | Total interest income, net/Total | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x24 | N/A | N/A | N/A | N/A | N/A | N/A |