| r0.1 | label_boi_a2/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | N/A | boi_RP:x24 |
| r0.2 | label_boi_a2/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | N/A | boi_RP:x24 |
| 1.1 | Deferred tax asset, net-see Note 8/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x430 | boi_RP:x24 |
| 1.2 | Deferred tax asset, net-see Note 8/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x430 | boi_RP:x24 |
| 2.1 | Assets transferred to ownership of the group as a result of settlement of problem loans/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x431 | boi_RP:x24 |
| 2.2 | Assets transferred to ownership of the group as a result of settlement of problem loans/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x431 | boi_RP:x24 |
| 3.1 | Surplus of asset plans over the employee benefit obligations/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x432 | boi_RP:x24 |
| 3.2 | Surplus of asset plans over the employee benefit obligations/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x432 | boi_RP:x24 |
| 4.1 | Assets received in respect to loans repaid/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x433 | boi_RP:x24 |
| 4.2 | Assets received in respect to loans repaid/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x433 | boi_RP:x24 |
| 5.1 | Expenses to be amortized on issuance of debentures, bonds and subordinated notes/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x435 | boi_RP:x24 |
| 5.2 | Expenses to be amortized on issuance of debentures, bonds and subordinated notes/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x435 | boi_RP:x24 |
| 6.1 | Other amortization expense/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x436 | boi_RP:x24 |
| 6.2 | Other amortization expense/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x436 | boi_RP:x24 |
| 7.1 | Total amortization expense/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x434 | boi_RP:x24 |
| 7.2 | Total amortization expense/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x434 | boi_RP:x24 |
| 8.1 | Usage-rights assets in respect of an operating lease/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1150 | boi_RP:x24 |
| 8.2 | Usage-rights assets in respect of an operating lease/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x1150 | boi_RP:x24 |
| 9.1 | Other receivables and prepayments (including gold)/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x437 | boi_RP:x24 |
| 9.2 | Other receivables and prepayments (including gold)/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x437 | boi_RP:x24 |
| 10.1 | Total other assets/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x41 | boi_RP:x24 |
| 10.2 | Total other assets/Bank Corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x41 | boi_RP:x24 |