| 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 nonperforming loans 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 nonperforming loans 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 nonperforming loans 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 nonperforming 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:x212 | N/A |
| 1.2 | Outstanding nonperforming 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:x212 | N/A |
| 1.3 | Outstanding nonperforming 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:x212 | N/A |
| 2.1 | Debts classified as nonperforming during the year/Commercial | boi_met:md1377 | 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:x212 | N/A |
| 2.2 | Debts classified as nonperforming during the year/Private | boi_met:md1377 | 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:x212 | N/A |
| 2.3 | Debts classified as nonperforming during the year/Total | boi_met:md1377 | 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:x212 | N/A |
| 3.1 | Debts that returned to accruing interest income classification/Commercial | boi_met:md1378 | 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 accruing interest income classification/Private | boi_met:md1378 | 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 accruing interest income classification/Total | boi_met:md1378 | 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 | Noneperforming debts written off/Commercial | boi_met:md1380 | 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:x212 | N/A |
| 4.2 | Noneperforming debts written off/Private | boi_met:md1380 | 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:x212 | N/A |
| 4.3 | Noneperforming debts written off/Total | boi_met:md1380 | 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:x212 | N/A |
| 5.1 | Nonperforming 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:x212 | N/A |
| 5.2 | Nonperforming 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:x212 | N/A |
| 5.3 | Nonperforming 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:x212 | N/A |
| 6.1 | Other/Commercial | boi_met:md1379 | 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:x212 | N/A |
| 6.2 | Other/Private | boi_met:md1379 | 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:x212 | N/A |
| 6.3 | Other/Total | boi_met:md1379 | 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:x212 | N/A |
| 7.1 | Outstanding nonperforming 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:x212 | N/A |
| 7.2 | Outstanding nonperforming 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:x212 | N/A |
| 7.3 | Outstanding nonperforming 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:x212 | N/A |
| r9.1 | Of which: nonperforming loans 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: nonperforming loans 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: nonperforming loans 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 | Outstanding nonperforming 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:x212 | boi_ST:x210 |
| 8.2 | Outstanding nonperforming 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:x212 | boi_ST:x210 |
| 8.3 | Outstanding nonperforming 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:x212 | boi_ST:x210 |
| 9.1 | Debts classified as nonperforming 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:x212 | boi_ST:x210 |
| 9.2 | Debts classified as nonperforming 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:x212 | boi_ST:x210 |
| 9.3 | Debts classified as nonperforming 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:x212 | boi_ST:x210 |
| 10.1 | Debts that returned to accruing interest income classification/Commercial | boi_met:md1378 | 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 returned to accruing interest income classification/Private | boi_met:md1378 | 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 returned to accruing interest income classification/Total | boi_met:md1378 | 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 | Impaired debts written off/Commercial | boi_met:md1380 | 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:x212 | boi_ST:x210 |
| 11.2 | Impaired debts written off/Private | boi_met:md1380 | 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:x212 | boi_ST:x210 |
| 11.3 | Impaired debts written off/Total | boi_met:md1380 | 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:x212 | boi_ST:x210 |
| 12.1 | Nonperforming 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:x212 | boi_ST:x210 |
| 12.2 | Nonperforming 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:x212 | boi_ST:x210 |
| 12.3 | Nonperforming 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:x212 | boi_ST:x210 |
| 13.1 | Other/Commercial | boi_met:md1379 | 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:x212 | boi_ST:x210 |
| 13.2 | Other/Private | boi_met:md1379 | 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:x212 | boi_ST:x210 |
| 13.3 | Other/Total | boi_met:md1379 | 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:x212 | boi_ST:x210 |
| 14.1 | Outstanding nonperforming 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:x212 | boi_ST:x210 |
| 14.2 | Outstanding nonperforming 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:x212 | boi_ST:x210 |
| 14.3 | Outstanding nonperforming 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:x212 | boi_ST:x210 |