| r0.1 | label_boi_a2/Commercial | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x4 | N/A | N/A |
| r0.2 | label_boi_a2/Private | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x15 | N/A | N/A |
| r0.3 | label_boi_a2/Total | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A |
| r1.1 | Transactions in impaired debts in respect of credit to the public/Commercial | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x4 | N/A | N/A |
| r1.2 | Transactions in impaired debts in respect of credit to the public/Private | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x15 | N/A | N/A |
| r1.3 | Transactions in impaired debts in respect of credit to the public/Total | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A |
| 1.1 | Outstanding impaired debts to the beginning of the year/Commercial | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | boi_RP:x22 | boi_SE:x4 | boi_ST:x3 | N/A |
| 1.2 | Outstanding impaired debts to the beginning of the year/Private | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | boi_RP:x22 | boi_SE:x15 | boi_ST:x3 | N/A |
| 1.3 | Outstanding impaired debts to the beginning of the year/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | boi_RP:x22 | boi_SE:x16 | boi_ST:x3 | N/A |
| 2.1 | Debts classified as impaired during the year/Commercial | boi_met:md1188 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | N/A |
| 2.2 | Debts classified as impaired during the year/Private | boi_met:md1188 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | N/A |
| 2.3 | Debts classified as impaired during the year/Total | boi_met:md1188 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | N/A |
| 3.1 | Debts that returned to non-impaired classification/Commercial | boi_met:md1189 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | N/A | N/A |
| 3.2 | Debts that returned to non-impaired classification/Private | boi_met:md1189 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | N/A | N/A |
| 3.3 | Debts that returned to non-impaired classification/Total | boi_met:md1189 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | N/A | N/A |
| 4.1 | Impaired debts written off/Commercial | boi_met:md1320 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | N/A |
| 4.2 | Impaired debts written off/Private | boi_met:md1320 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | N/A |
| 4.3 | Impaired debts written off/Total | boi_met:md1320 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | N/A |
| 5.1 | Impaired debts that were repaid/Commercial | boi_met:md1321 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | N/A |
| 5.2 | Impaired debts that were repaid/Private | boi_met:md1321 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | N/A |
| 5.3 | Impaired debts that were repaid/Total | boi_met:md1321 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | N/A |
| 6.1 | Other/Commercial | boi_met:md1322 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | N/A |
| 6.2 | Other/Private | boi_met:md1322 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | N/A |
| 6.3 | Other/Total | boi_met:md1322 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | N/A |
| 7.1 | Outstanding impaired debts to year-end/Commercial | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | N/A |
| 7.2 | Outstanding impaired debts to year-end/Private | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | N/A |
| 7.3 | Outstanding impaired debts to year-end/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | N/A |
| r9.1 | Of which: Impaired debts under restructuring transactions/Commercial | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x4 | N/A | boi_ST:x210 |
| r9.2 | Of which: Impaired debts under restructuring transactions/Private | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x15 | N/A | boi_ST:x210 |
| r9.3 | Of which: Impaired debts under restructuring transactions/Total | | | | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x16 | N/A | boi_ST:x210 |
| 8.1 | Impaired debts under restructuring to the beginning of the year/Commercial | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | boi_RP:x22 | boi_SE:x4 | boi_ST:x3 | boi_ST:x210 |
| 8.2 | Impaired debts under restructuring to the beginning of the year/Private | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | boi_RP:x22 | boi_SE:x15 | boi_ST:x3 | boi_ST:x210 |
| 8.3 | Impaired debts under restructuring to the beginning of the year/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | boi_RP:x22 | boi_SE:x16 | boi_ST:x3 | boi_ST:x210 |
| 9.1 | Reorganizations carried out during the year/Commercial | boi_met:md1323 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | boi_ST:x210 |
| 9.2 | Reorganizations carried out during the year/Private | boi_met:md1323 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | boi_ST:x210 |
| 9.3 | Reorganizations carried out during the year/Total | boi_met:md1323 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | boi_ST:x210 |
| 10.1 | Debts that were returned to unimpaired status due to later reorganization/Commercial | boi_met:md1189 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | N/A | boi_ST:x210 |
| 10.2 | Debts that were returned to unimpaired status due to later reorganization/Private | boi_met:md1189 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | N/A | boi_ST:x210 |
| 10.3 | Debts that were returned to unimpaired status due to later reorganization/Total | boi_met:md1189 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | N/A | boi_ST:x210 |
| 11.1 | Debts in reorganization that were written off/Commercial | boi_met:md1320 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | boi_ST:x210 |
| 11.2 | Debts in reorganization that were written off/Private | boi_met:md1320 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | boi_ST:x210 |
| 11.3 | Debts in reorganization that were written off/Total | boi_met:md1320 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | boi_ST:x210 |
| 12.1 | Debts in reorganization that were repaid/Commercial | boi_met:md1321 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | boi_ST:x210 |
| 12.2 | Debts in reorganization that were repaid/Private | boi_met:md1321 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | boi_ST:x210 |
| 12.3 | Debts in reorganization that were repaid/Total | boi_met:md1321 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | boi_ST:x210 |
| 13.1 | Other/Commercial | boi_met:md1322 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | boi_ST:x210 |
| 13.2 | Other/Private | boi_met:md1322 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | boi_ST:x210 |
| 13.3 | Other/Total | boi_met:md1322 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | boi_MU:x1 | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | boi_ST:x210 |
| 14.1 | Impaired debts under restructuring to year-end/Commercial | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x4 | boi_ST:x3 | boi_ST:x210 |
| 14.2 | Impaired debts under restructuring to year-end/Private | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x15 | boi_ST:x3 | boi_ST:x210 |
| 14.3 | Impaired debts under restructuring to year-end/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x640 | N/A | boi_RP:x24 | N/A | boi_SE:x16 | boi_ST:x3 | boi_ST:x210 |