| r0.1 | label_boi_a2/Average balance | boi_met:md86 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | boi_GA:x1 | N/A | N/A | N/A | N/A | boi_RP:x19 |
| r0.2 | label_boi_a2/Financing income (expenses) | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | boi_GA:x1 | boi_MC:x125 | N/A | N/A | N/A | boi_RP:x19 |
| r0.3 | label_boi_a2/Rate of income (expense) | boi_met:pd90 | num:percentItemType | instant | N/A | boi_CS:x2 | N/A | boi_GA:x1 | N/A | N/A | N/A | N/A | boi_RP:x19 |
| r0.4 | label_boi_a2/Average balance | boi_met:md86 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | boi_GA:x1 | N/A | N/A | N/A | boi_MU:x1 | boi_RP:x19 |
| r0.5 | label_boi_a2/Financing income (expenses) | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | boi_GA:x1 | boi_MC:x125 | N/A | N/A | boi_MU:x1 | boi_RP:x19 |
| r0.6 | label_boi_a2/Rate of income (expense) | boi_met:pd90 | num:percentItemType | instant | N/A | boi_CS:x2 | N/A | boi_GA:x1 | N/A | N/A | N/A | boi_MU:x1 | boi_RP:x19 |
| r1.1 | Foreign currency (incl. foreign-currency indexed local currency)/Average balance | boi_met:md86 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | N/A | N/A | boi_RP:x19 |
| r1.2 | Foreign currency (incl. foreign-currency indexed local currency)/Financing income (expenses) | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | boi_MC:x125 | boi_MC:x962 | N/A | N/A | boi_RP:x19 |
| r1.3 | Foreign currency (incl. foreign-currency indexed local currency)/Rate of income (expense) | boi_met:pd90 | num:percentItemType | instant | N/A | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | N/A | N/A | boi_RP:x19 |
| r1.4 | Foreign currency (incl. foreign-currency indexed local currency)/Average balance | boi_met:md86 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | N/A | boi_MU:x1 | boi_RP:x19 |
| r1.5 | Foreign currency (incl. foreign-currency indexed local currency)/Financing income (expenses) | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | boi_MC:x125 | boi_MC:x962 | N/A | boi_MU:x1 | boi_RP:x19 |
| r1.6 | Foreign currency (incl. foreign-currency indexed local currency)/Rate of income (expense) | boi_met:pd90 | num:percentItemType | instant | N/A | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | N/A | boi_MU:x1 | boi_RP:x19 |
| 7.1 | Total interest-bearing assets/Average balance | boi_met:md86 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | boi_MC:x1 | N/A | boi_RP:x19 |
| 7.2 | Total interest-bearing assets/Financing income (expenses) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | boi_MC:x125 | boi_MC:x962 | boi_MC:x1 | N/A | boi_RP:x19 |
| 7.3 | Total interest-bearing assets/Rate of income (expense) | boi_met:pd90 | num:percentItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | boi_MC:x1 | N/A | boi_RP:x19 |
| 7.4 | Total interest-bearing assets/Average balance | boi_met:md86 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | boi_MC:x1 | boi_MU:x1 | boi_RP:x19 |
| 7.5 | Total interest-bearing assets/Financing income (expenses) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | boi_MC:x125 | boi_MC:x962 | boi_MC:x1 | boi_MU:x1 | boi_RP:x19 |
| 7.6 | Total interest-bearing assets/Rate of income (expense) | boi_met:pd90 | num:percentItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | boi_MC:x1 | boi_MU:x1 | boi_RP:x19 |
| 8.1 | Total interest-bearing liabilities/Average balance | boi_met:md86 | xbrli:monetaryItemType | instant | boi_BC:x2 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | boi_MC:x3 | N/A | boi_RP:x19 |
| 8.2 | Total interest-bearing liabilities/Financing income (expenses) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x2 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | boi_MC:x125 | boi_MC:x962 | boi_MC:x3 | N/A | boi_RP:x19 |
| 8.3 | Total interest-bearing liabilities/Rate of income (expense) | boi_met:pd90 | num:percentItemType | instant | boi_BC:x2 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | boi_MC:x3 | N/A | boi_RP:x19 |
| 8.4 | Total interest-bearing liabilities/Average balance | boi_met:md86 | xbrli:monetaryItemType | instant | boi_BC:x2 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | boi_MC:x3 | boi_MU:x1 | boi_RP:x19 |
| 8.5 | Total interest-bearing liabilities/Financing income (expenses) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x2 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | boi_MC:x125 | boi_MC:x962 | boi_MC:x3 | boi_MU:x1 | boi_RP:x19 |
| 8.6 | Total interest-bearing liabilities/Rate of income (expense) | boi_met:pd90 | num:percentItemType | instant | boi_BC:x2 | boi_CS:x2 | boi_CU:x15 | boi_GA:x1 | N/A | boi_MC:x962 | boi_MC:x3 | boi_MU:x1 | boi_RP:x19 |