| r0.1 | label_boi_a2/Consolidated | | | | N/A | N/A | boi_CS:x2 | N/A | N/A | boi_RP:x24 | N/A |
| r0.2 | label_boi_a2/Company | | | | N/A | N/A | boi_CS:x1 | N/A | N/A | boi_RP:x24 | N/A |
| 1.1 | cash and bank deposits/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x9 | N/A | boi_RP:x24 | boi_SE:x1 |
| 1.2 | cash and bank deposits/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x9 | N/A | boi_RP:x24 | boi_SE:x1 |
| 2.1 | Sums receivable on account of credit card activity/Consolidated | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x89 |
| 2.2 | Sums receivable on account of credit card activity/Company | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x89 |
| 3.1 | Credit loss provision/Consolidated | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x89 |
| 3.2 | Credit loss provision/Company | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x89 |
| 4.1 | Sums receivable on account of credit card activity, net/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x89 |
| 4.2 | Sums receivable on account of credit card activity, net/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x89 |
| 5.1 | Securities/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x29 | N/A | boi_RP:x24 | N/A |
| 5.2 | Securities/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x29 | N/A | boi_RP:x24 | N/A |
| 6.1 | Securities borrowed or acquired under repurchase agreements/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x28 | N/A | boi_RP:x24 | N/A |
| 6.2 | Securities borrowed or acquired under repurchase agreements/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x28 | N/A | boi_RP:x24 | N/A |
| 7.1 | Investments in included companies/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x54 | N/A | boi_RP:x24 | N/A |
| 7.2 | Investments in included companies/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x54 | N/A | boi_RP:x24 | N/A |
| 8.1 | Buildings and equipment/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x6 | N/A | boi_RP:x24 | N/A |
| 8.2 | Buildings and equipment/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x6 | N/A | boi_RP:x24 | N/A |
| 9.1 | Other assets/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x443 | N/A | boi_RP:x24 | N/A |
| 9.2 | Other assets/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x443 | N/A | boi_RP:x24 | N/A |
| 10.1 | Total assets/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x1 | N/A | boi_RP:x24 | N/A |
| 10.2 | Total assets/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x1 | N/A | boi_RP:x24 | N/A |
| 11.1 | Credit from banking corporations/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x17 | N/A | boi_RP:x24 | boi_SE:x1 |
| 11.2 | Credit from banking corporations/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x1 | boi_MC:x17 | N/A | boi_RP:x24 | boi_SE:x1 |
| 12.1 | Sums payable on account of credit card activity/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x17 | N/A | boi_RP:x24 | boi_SE:x89 |
| 12.2 | Sums payable on account of credit card activity/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x1 | boi_MC:x17 | N/A | boi_RP:x24 | boi_SE:x89 |
| 13.1 | Securities lent or sold under repurchase agreements/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x28 | N/A | boi_RP:x24 | N/A |
| 13.2 | Securities lent or sold under repurchase agreements/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x1 | boi_MC:x28 | N/A | boi_RP:x24 | N/A |
| 14.1 | Bonds and subordinated capital notes/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x15 | N/A | boi_RP:x24 | N/A |
| 14.2 | Bonds and subordinated capital notes/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x1 | boi_MC:x15 | N/A | boi_RP:x24 | N/A |
| 15.1 | Other liabilities/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x472 | N/A | boi_RP:x24 | N/A |
| 15.2 | Other liabilities/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x1 | boi_MC:x472 | N/A | boi_RP:x24 | N/A |
| 16.1 | Total liabilities/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x2 | boi_MC:x3 | N/A | boi_RP:x24 | N/A |
| 16.2 | Total liabilities/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x2 | N/A | boi_CS:x1 | boi_MC:x3 | N/A | boi_RP:x24 | N/A |
| 17.1 | Equity attributed to shareholders in credit card company/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | N/A | boi_RP:x24 | N/A |
| 17.2 | Equity attributed to shareholders in credit card company/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x1 | boi_MC:x2 | N/A | boi_RP:x24 | N/A |
| 18.1 | Non-controlling rights/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | N/A | boi_RP:x24 | N/A |
| 18.2 | Non-controlling rights/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x1 | boi_MC:x2 | N/A | boi_RP:x24 | N/A |
| 19.1 | Total equity/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | N/A | boi_RP:x24 | N/A |
| 19.2 | Total equity/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x1 | boi_MC:x2 | N/A | boi_RP:x24 | N/A |
| 20.1 | Total liabilities and equity/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x4 | N/A | boi_CS:x2 | N/A | N/A | boi_RP:x24 | N/A |
| 20.2 | Total liabilities and equity/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x4 | N/A | boi_CS:x1 | N/A | N/A | boi_RP:x24 | N/A |
| 21.1 | Thereof: securities pledged to lenders/Consolidated | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x2 | boi_MC:x29 | boi_MC:x29 | boi_RP:x24 | N/A |
| 21.2 | Thereof: securities pledged to lenders/Company | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_CS:x1 | boi_MC:x29 | boi_MC:x29 | boi_RP:x24 | N/A |