| r0.1 | label_boi_a2/Unaudited | | | | N/A | N/A | boi_CS:x2 | N/A | N/A | boi_RP:x19 |
| r0.2 | label_boi_a2/Audited | | | | N/A | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x24 |
| r1.1 | Income/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | N/A | boi_RP:x19 |
| r1.2 | Income/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x24 |
| 1.1 | Income from credit card transactions/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | N/A | boi_RP:x19 |
| 1.2 | Income from credit card transactions/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_MU:x1 | boi_RP:x24 |
| 2.1 | Net interest income/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | N/A | boi_RP:x19 |
| 2.2 | Net interest income/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_MU:x1 | boi_RP:x24 |
| 3.1 | Other income/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | N/A | boi_RP:x19 |
| 3.2 | Other income/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_MU:x1 | boi_RP:x24 |
| 4.1 | Total income/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | N/A | boi_RP:x19 |
| 4.2 | Total income/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_MU:x1 | boi_RP:x24 |
| r6.1 | Expenses/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | N/A | boi_RP:x19 |
| r6.2 | Expenses/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x24 |
| 5.1 | On credit losses/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x126 | N/A | boi_RP:x19 |
| 5.2 | On credit losses/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x126 | boi_MU:x1 | boi_RP:x24 |
| 6.1 | Operating/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | N/A | boi_RP:x19 |
| 6.2 | Operating/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_MU:x1 | boi_RP:x24 |
| 7.1 | Selling and marketing/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x459 | N/A | boi_RP:x19 |
| 7.2 | Selling and marketing/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x459 | boi_MU:x1 | boi_RP:x24 |
| 8.1 | Administrative and general/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x460 | N/A | boi_RP:x19 |
| 8.2 | Administrative and general/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x460 | boi_MU:x1 | boi_RP:x24 |
| 9.1 | Payments to banks/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | N/A | boi_RP:x19 |
| 9.2 | Payments to banks/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_MU:x1 | boi_RP:x24 |
| 10.1 | Total expenses/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x457 | N/A | boi_RP:x19 |
| 10.2 | Total expenses/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x457 | boi_MU:x1 | boi_RP:x24 |
| 11.1 | Profit before taxes/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x123 | N/A | boi_RP:x19 |
| 11.2 | Profit before taxes/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x123 | boi_MU:x1 | boi_RP:x24 |
| 12.1 | Provision for taxes on profit/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x190 | N/A | boi_RP:x19 |
| 12.2 | Provision for taxes on profit/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x190 | boi_MU:x1 | boi_RP:x24 |
| 13.1 | Profit after taxes/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x122 | N/A | boi_RP:x19 |
| 13.2 | Profit after taxes/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x122 | boi_MU:x1 | boi_RP:x24 |
| 14.1 | Company's share in profit of included companies after tax effect/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x191 | N/A | boi_RP:x19 |
| 14.2 | Company's share in profit of included companies after tax effect/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x191 | boi_MU:x1 | boi_RP:x24 |
| r17.1 | Net profit/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x19 |
| r17.2 | Net profit/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x24 |
| 15.1 | Before attribution to minority interest/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x19 |
| 15.2 | Before attribution to minority interest/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x24 |
| 16.1 | Attributed to minority interest/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x19 |
| 16.2 | Attributed to minority interest/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x24 |
| 17.1 | Attributed to the credit card company's shareholders/Unaudited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x19 |
| 17.2 | Attributed to the credit card company's shareholders/Audited | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x24 |
| r21.1 | Net profit per ordinary share/Unaudited | | | | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x19 |
| r21.2 | Net profit per ordinary share/Audited | | | | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x24 |
| 18.1 | Basic profit: Attributed to the credit card company's shareholders/Unaudited | boi_met:md81 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x19 |
| 18.2 | Basic profit: Attributed to the credit card company's shareholders/Audited | boi_met:md81 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x24 |
| 19.1 | Diluted profit: Attributed to the credit card company's shareholders/Unaudited | boi_met:md82 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x19 |
| 19.2 | Diluted profit: Attributed to the credit card company's shareholders/Audited | boi_met:md82 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x24 |