| r0.1 | label_boi_a2/Consolidated | | | | N/A | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x25 |
| r0.2 | label_boi_a2/Company | | | | N/A | N/A | boi_CS:x1 | N/A | boi_MU:x1 | boi_RP:x25 |
| r1.1 | Income/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x25 |
| r1.2 | Income/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | N/A | boi_MU:x1 | boi_RP:x25 |
| 1.1 | Income from credit card transactions/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_MU:x1 | boi_RP:x25 |
| 1.2 | Income from credit card transactions/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x281 | boi_MU:x1 | boi_RP:x25 |
| 2.1 | Net interest income/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_MU:x1 | boi_RP:x25 |
| 2.2 | Net interest income/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x125 | boi_MU:x1 | boi_RP:x25 |
| 3.1 | Other income/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_MU:x1 | boi_RP:x25 |
| 3.2 | Other income/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x456 | boi_MU:x1 | boi_RP:x25 |
| 4.1 | Total income/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_MU:x1 | boi_RP:x25 |
| 4.2 | Total income/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x455 | boi_MU:x1 | boi_RP:x25 |
| r6.1 | Expenses/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x25 |
| r6.2 | Expenses/Company | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x1 | N/A | boi_MU:x1 | boi_RP:x25 |
| 5.1 | Credit loss expenses/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x126 | boi_MU:x1 | boi_RP:x25 |
| 5.2 | Credit loss expenses/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x1 | boi_MC:x126 | boi_MU:x1 | boi_RP:x25 |
| 6.1 | Operational/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_MU:x1 | boi_RP:x25 |
| 6.2 | Operational/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x1 | boi_MC:x458 | boi_MU:x1 | boi_RP:x25 |
| 7.1 | Sales and marketing/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x459 | boi_MU:x1 | boi_RP:x25 |
| 7.2 | Sales and marketing/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x1 | boi_MC:x459 | boi_MU:x1 | boi_RP:x25 |
| 8.1 | Administrative and general/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x460 | boi_MU:x1 | boi_RP:x25 |
| 8.2 | Administrative and general/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x1 | boi_MC:x460 | boi_MU:x1 | boi_RP:x25 |
| 9.1 | Payments to banks/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_MU:x1 | boi_RP:x25 |
| 9.2 | Payments to banks/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x1 | boi_MC:x461 | boi_MU:x1 | boi_RP:x25 |
| 10.1 | Total expenses/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x457 | boi_MU:x1 | boi_RP:x25 |
| 10.2 | Total expenses/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x1 | boi_MC:x457 | boi_MU:x1 | boi_RP:x25 |
| 11.1 | Pre-tax profit/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x123 | boi_MU:x1 | boi_RP:x25 |
| 11.2 | Pre-tax profit/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x123 | boi_MU:x1 | boi_RP:x25 |
| 12.1 | Provision for taxes on profit/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x190 | boi_MU:x1 | boi_RP:x25 |
| 12.2 | Provision for taxes on profit/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x1 | boi_MC:x190 | boi_MU:x1 | boi_RP:x25 |
| 13.1 | Post-tax profit/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x122 | boi_MU:x1 | boi_RP:x25 |
| 13.2 | Post-tax profit/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x122 | boi_MU:x1 | boi_RP:x25 |
| 14.1 | Company's share in profit of included companies after effect of tax/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x191 | boi_MU:x1 | boi_RP:x25 |
| 14.2 | Company's share in profit of included companies after effect of tax/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x191 | boi_MU:x1 | boi_RP:x25 |
| r17.1 | Net profit/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| r17.2 | Net profit/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 15.1 | before attribution to holders of noncontrolling rights/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 15.2 | before attribution to holders of noncontrolling rights/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x1 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 16.1 | attributed to holders of noncontrolling rights/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 16.2 | attributed to holders of noncontrolling rights/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x1 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 17.1 | Net profit attributed to shareholders in credit card company/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 17.2 | Net profit attributed to shareholders in credit card company/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x1 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| r21.1 | Net profit per share/Consolidated | | | | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| r21.2 | Net profit per share/Company | | | | boi_BC:x11 | boi_CN:x1 | boi_CS:x1 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 18.1 | Basic profit: Attributed to shareholders in credit card company/Consolidated | boi_met:md81 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 18.2 | Basic profit: Attributed to shareholders in credit card company/Company | boi_met:md81 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x1 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 19.1 | Diluted profit: Attributed to shareholders in credit card company/Consolidated | boi_met:md82 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |
| 19.2 | Diluted profit: Attributed to shareholders in credit card company/Company | boi_met:md82 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x1 | boi_MC:x121 | boi_MU:x1 | boi_RP:x25 |