| r0.1 | label_boi_a2/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | boi_TI:x38 |
| r0.2 | label_boi_a2/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | boi_TI:x85 |
| r0.3 | label_boi_a2/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | boi_TI:x19 |
| r0.4 | label_boi_a2/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | boi_TI:x23 |
| r0.5 | label_boi_a2/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | N/A |
| r1.1 | Balance sheet Credit exposure/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | boi_TI:x38 |
| r1.2 | Balance sheet Credit exposure/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | boi_TI:x85 |
| r1.3 | Balance sheet Credit exposure/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | boi_TI:x19 |
| r1.4 | Balance sheet Credit exposure/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | boi_TI:x23 |
| r1.5 | Balance sheet Credit exposure/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | N/A | boi_RP:x24 | N/A | N/A |
| 1.1 | Commercial/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x4 | boi_TI:x38 |
| 1.2 | Commercial/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x4 | boi_TI:x85 |
| 1.3 | Commercial/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x4 | boi_TI:x19 |
| 1.4 | Commercial/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x4 | boi_TI:x23 |
| 1.5 | Commercial/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x4 | N/A |
| 2.1 | Private individuals-housing loans/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x35 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | boi_TI:x38 |
| 2.2 | Private individuals-housing loans/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x35 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | boi_TI:x85 |
| 2.3 | Private individuals-housing loans/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x35 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | boi_TI:x19 |
| 2.4 | Private individuals-housing loans/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x35 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | boi_TI:x23 |
| 2.5 | Private individuals-housing loans/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x35 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | N/A |
| 3.1 | Private individuals-other/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x38 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | boi_TI:x38 |
| 3.2 | Private individuals-other/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x38 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | boi_TI:x85 |
| 3.3 | Private individuals-other/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x38 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | boi_TI:x19 |
| 3.4 | Private individuals-other/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x38 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | boi_TI:x23 |
| 3.5 | Private individuals-other/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x38 | boi_CS:x2 | boi_MC:x1086 | boi_RP:x24 | boi_SE:x15 | N/A |
| 4.1 | Assets in respect of derivative instruments/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x18 | boi_RP:x24 | boi_SE:x16 | boi_TI:x38 |
| 4.2 | Assets in respect of derivative instruments/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x18 | boi_RP:x24 | boi_SE:x16 | boi_TI:x85 |
| 4.3 | Assets in respect of derivative instruments/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x18 | boi_RP:x24 | boi_SE:x16 | boi_TI:x19 |
| 4.4 | Assets in respect of derivative instruments/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x18 | boi_RP:x24 | boi_SE:x16 | boi_TI:x23 |
| 4.5 | Assets in respect of derivative instruments/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x18 | boi_RP:x24 | boi_SE:x16 | N/A |
| 5.1 | Total public/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x16 | boi_TI:x38 |
| 5.2 | Total public/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x16 | boi_TI:x85 |
| 5.3 | Total public/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x16 | boi_TI:x19 |
| 5.4 | Total public/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x16 | boi_TI:x23 |
| 5.5 | Total public/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x16 | N/A |
| 6.1 | Government and banks/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x356 | boi_TI:x38 |
| 6.2 | Government and banks/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x356 | boi_TI:x85 |
| 6.3 | Government and banks/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x356 | boi_TI:x19 |
| 6.4 | Government and banks/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x356 | boi_TI:x23 |
| 6.5 | Government and banks/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | boi_SE:x356 | N/A |
| 7.1 | Total balance sheet Credit exposure/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | N/A | boi_TI:x38 |
| 7.2 | Total balance sheet Credit exposure/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | N/A | boi_TI:x85 |
| 7.3 | Total balance sheet Credit exposure/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | N/A | boi_TI:x19 |
| 7.4 | Total balance sheet Credit exposure/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | N/A | boi_TI:x23 |
| 7.5 | Total balance sheet Credit exposure/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x922 | boi_RP:x24 | N/A | N/A |
| 8.1 | Of which: debentures/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x15 | boi_RP:x24 | N/A | boi_TI:x38 |
| 8.2 | Of which: debentures/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x15 | boi_RP:x24 | N/A | boi_TI:x85 |
| 8.3 | Of which: debentures/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x15 | boi_RP:x24 | N/A | boi_TI:x19 |
| 8.4 | Of which: debentures/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x15 | boi_RP:x24 | N/A | boi_TI:x23 |
| 8.5 | Of which: debentures/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x15 | boi_RP:x24 | N/A | N/A |
| 9.1 | Total off balance sheet Credit exposure/Up to one year | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_MC:x65 | boi_RP:x24 | N/A | boi_TI:x38 |
| 9.2 | Total off balance sheet Credit exposure/Over a year and up to 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_MC:x65 | boi_RP:x24 | N/A | boi_TI:x85 |
| 9.3 | Total off balance sheet Credit exposure/Over 5 years | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_MC:x65 | boi_RP:x24 | N/A | boi_TI:x19 |
| 9.4 | Total off balance sheet Credit exposure/Without fixed maturity | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_MC:x65 | boi_RP:x24 | N/A | boi_TI:x23 |
| 9.5 | Total off balance sheet Credit exposure/Total credit exposure | boi_met:mi10 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_MC:x65 | boi_RP:x24 | N/A | N/A |