| r0.1 | label_boi_a2/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x74 | N/A |
| r0.2 | label_boi_a2/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x73 | N/A |
| r0.3 | label_boi_a2/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x72 | N/A |
| r0.4 | label_boi_a2/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x75 | N/A |
| r0.5 | label_boi_a2/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x76 | N/A |
| r0.6 | label_boi_a2/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x19 | N/A | N/A |
| r1.1 | Income/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x74 | N/A |
| r1.2 | Income/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x73 | N/A |
| r1.3 | Income/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x72 | N/A |
| r1.4 | Income/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x75 | N/A |
| r1.5 | Income/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_RP:x19 | boi_SE:x76 | N/A |
| r1.6 | Income/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_RP:x19 | N/A | N/A |
| 1.1 | Commission income from externals/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x74 | boi_SE:x44 |
| 1.2 | Commission income from externals/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x73 | boi_SE:x44 |
| 1.3 | Commission income from externals/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x72 | boi_SE:x44 |
| 1.4 | Commission income from externals/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x75 | boi_SE:x44 |
| 1.5 | Commission income from externals/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x76 | boi_SE:x44 |
| 1.6 | Commission income from externals/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | N/A | boi_SE:x44 |
| 2.1 | Inter-segment commission income/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x74 | boi_SE:x45 |
| 2.2 | Inter-segment commission income/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x73 | boi_SE:x45 |
| 2.3 | Inter-segment commission income/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x72 | boi_SE:x45 |
| 2.4 | Inter-segment commission income/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x75 | boi_SE:x45 |
| 2.5 | Inter-segment commission income/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x76 | boi_SE:x45 |
| 2.6 | Inter-segment commission income/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | N/A | boi_SE:x45 |
| 3.1 | Total commission income/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x74 | N/A |
| 3.2 | Total commission income/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x73 | N/A |
| 3.3 | Total commission income/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x72 | N/A |
| 3.4 | Total commission income/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x75 | N/A |
| 3.5 | Total commission income/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | boi_SE:x76 | N/A |
| 3.6 | Total commission income/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_RP:x19 | N/A | N/A |
| 4.1 | Net interest income/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_RP:x19 | boi_SE:x74 | N/A |
| 4.2 | Net interest income/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_RP:x19 | boi_SE:x73 | N/A |
| 4.3 | Net interest income/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_RP:x19 | boi_SE:x72 | N/A |
| 4.4 | Net interest income/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_RP:x19 | boi_SE:x75 | N/A |
| 4.5 | Net interest income/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_RP:x19 | boi_SE:x76 | N/A |
| 4.6 | Net interest income/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_RP:x19 | N/A | N/A |
| 5.1 | Other income/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_RP:x19 | boi_SE:x74 | N/A |
| 5.2 | Other income/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_RP:x19 | boi_SE:x73 | N/A |
| 5.3 | Other income/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_RP:x19 | boi_SE:x72 | N/A |
| 5.4 | Other income/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_RP:x19 | boi_SE:x75 | N/A |
| 5.5 | Other income/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_RP:x19 | boi_SE:x76 | N/A |
| 5.6 | Other income/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_RP:x19 | N/A | N/A |
| 6.1 | Total income/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_RP:x19 | boi_SE:x74 | N/A |
| 6.2 | Total income/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_RP:x19 | boi_SE:x73 | N/A |
| 6.3 | Total income/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_RP:x19 | boi_SE:x72 | N/A |
| 6.4 | Total income/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_RP:x19 | boi_SE:x75 | N/A |
| 6.5 | Total income/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_RP:x19 | boi_SE:x76 | N/A |
| 6.6 | Total income/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_RP:x19 | N/A | N/A |
| 7.1 | Operating expenses/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_RP:x19 | boi_SE:x74 | N/A |
| 7.2 | Operating expenses/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_RP:x19 | boi_SE:x73 | N/A |
| 7.3 | Operating expenses/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_RP:x19 | boi_SE:x72 | N/A |
| 7.4 | Operating expenses/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_RP:x19 | boi_SE:x75 | N/A |
| 7.5 | Operating expenses/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_RP:x19 | boi_SE:x76 | N/A |
| 7.6 | Operating expenses/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_RP:x19 | N/A | N/A |
| 8.1 | Payments to banks/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_RP:x19 | boi_SE:x74 | N/A |
| 8.2 | Payments to banks/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_RP:x19 | boi_SE:x73 | N/A |
| 8.3 | Payments to banks/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_RP:x19 | boi_SE:x72 | N/A |
| 8.4 | Payments to banks/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_RP:x19 | boi_SE:x75 | N/A |
| 8.5 | Payments to banks/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_RP:x19 | boi_SE:x76 | N/A |
| 8.6 | Payments to banks/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_RP:x19 | N/A | N/A |
| 9.1 | Net profit attributed to company's shareholders/Settlement segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_RP:x19 | boi_SE:x74 | N/A |
| 9.2 | Net profit attributed to company's shareholders/Issue segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_RP:x19 | boi_SE:x73 | N/A |
| 9.3 | Net profit attributed to company's shareholders/Finance segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_RP:x19 | boi_SE:x72 | N/A |
| 9.4 | Net profit attributed to company's shareholders/Other segment | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_RP:x19 | boi_SE:x75 | N/A |
| 9.5 | Net profit attributed to company's shareholders/Reconciliations | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_RP:x19 | boi_SE:x76 | N/A |
| 9.6 | Net profit attributed to company's shareholders/Total consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_RP:x19 | N/A | N/A |