| r0.1 | label_boi_a2/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_RP:x13 | N/A |
| 1.1 | Assets: cash and bank deposits/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x9 | boi_RP:x13 | boi_SE:x1 |
| 2.1 | Sums receivable on account of net credit card activity/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x8 | boi_RP:x13 | boi_SE:x89 |
| 3.1 | Securities/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x29 | boi_RP:x13 | N/A |
| 4.1 | Securities borrowed or acquired under repurchase agreements/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x28 | boi_RP:x13 | N/A |
| 5.1 | Investments in included companies/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x54 | boi_RP:x13 | N/A |
| 6.1 | Buildings and equipment/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x6 | boi_RP:x13 | N/A |
| 7.1 | Other assets/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x443 | boi_RP:x13 | N/A |
| 8.1 | Total assets/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x1 | boi_RP:x13 | N/A |
| 9.1 | Liabilities and capital: credit from banking corporations/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x17 | boi_RP:x13 | boi_SE:x1 |
| 10.1 | Sums payable on account of credit card activity/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x17 | boi_RP:x13 | boi_SE:x89 |
| 11.1 | Securities lent or sold under repurchase agreements/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x28 | boi_RP:x13 | N/A |
| 12.1 | Bonds and subordinated capital notes/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x15 | boi_RP:x13 | N/A |
| 13.1 | Other liabilities/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x472 | boi_RP:x13 | N/A |
| 14.1 | Total liabilities/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x3 | boi_RP:x13 | N/A |
| 15.1 | Equity attributed to shareholders in credit card company/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_RP:x13 | N/A |
| 16.1 | Non-controlling rights/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_RP:x13 | N/A |
| 17.1 | Total equity/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_RP:x13 | N/A |
| 18.1 | Total liabilities and equity/Consolidated (incl. companies reporting as company only) | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x4 | N/A | boi_CS:x2 | N/A | boi_RP:x13 | N/A |