| r0.1 | label_boi_a2/Share capital | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | N/A | N/A | boi_RP:x25 | N/A |
| r0.2 | label_boi_a2/Receipts on account of shares and perpetual liabilities | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | N/A | N/A | boi_RP:x25 | N/A |
| r0.3 | label_boi_a2/Permium | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | N/A | N/A | boi_RP:x25 | N/A |
| r0.4 | label_boi_a2/Share-based payment transactions and others | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | N/A | N/A | boi_RP:x25 | N/A |
| r0.5 | label_boi_a2/Others | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | N/A | N/A | boi_RP:x25 | N/A |
| r0.6 | label_boi_a2/Total share capital and capital reserve | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | N/A | N/A | boi_RP:x25 | N/A |
| r0.7 | label_boi_a2/Other comprehensive profit | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | N/A | N/A | boi_RP:x25 | N/A |
| r0.8 | label_boi_a2/Suplus/ deficit | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | N/A | N/A | boi_RP:x25 | N/A |
| r0.9 | label_boi_a2/Other capital items | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | N/A | N/A | boi_RP:x25 | N/A |
| r0.10 | label_boi_a2/Total Attributed to shareholders of the banking corporation | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |
| r0.11 | label_boi_a2/Non controlling interests | | | | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |
| r0.12 | label_boi_a2/Total capital | | | | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |
| 1.1 | Balance as at 1 January/Share capital | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.2 | Balance as at 1 January/Receipts on account of shares and perpetual liabilities | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.3 | Balance as at 1 January/Permium | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.4 | Balance as at 1 January/Share-based payment transactions and others | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.5 | Balance as at 1 January/Others | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.6 | Balance as at 1 January/Total share capital and capital reserve | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.7 | Balance as at 1 January/Other comprehensive profit | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.8 | Balance as at 1 January/Suplus/ deficit | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.9 | Balance as at 1 January/Other capital items | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.10 | Balance as at 1 January/Total Attributed to shareholders of the banking corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.11 | Balance as at 1 January/Non controlling interests | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 1.12 | Balance as at 1 January/Total capital | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | boi_RP:x22 |
| 2.1 | Other reconciliations/Share capital | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | N/A | N/A | boi_RP:x25 | N/A |
| 2.2 | Other reconciliations/Receipts on account of shares and perpetual liabilities | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | N/A | N/A | boi_RP:x25 | N/A |
| 2.3 | Other reconciliations/Permium | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | N/A | N/A | boi_RP:x25 | N/A |
| 2.4 | Other reconciliations/Share-based payment transactions and others | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | N/A | N/A | boi_RP:x25 | N/A |
| 2.5 | Other reconciliations/Others | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | N/A | N/A | boi_RP:x25 | N/A |
| 2.6 | Other reconciliations/Total share capital and capital reserve | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | N/A | N/A | boi_RP:x25 | N/A |
| 2.7 | Other reconciliations/Other comprehensive profit | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | N/A | N/A | boi_RP:x25 | N/A |
| 2.8 | Other reconciliations/Suplus/ deficit | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | N/A | N/A | boi_RP:x25 | N/A |
| 2.9 | Other reconciliations/Other capital items | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | N/A | N/A | boi_RP:x25 | N/A |
| 2.10 | Other reconciliations/Total Attributed to shareholders of the banking corporation | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |
| 2.11 | Other reconciliations/Non controlling interests | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |
| 2.12 | Other reconciliations/Total capital | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |
| 3.1 | Net profit for the accounting year/Share capital | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.2 | Net profit for the accounting year/Receipts on account of shares and perpetual liabilities | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.3 | Net profit for the accounting year/Permium | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.4 | Net profit for the accounting year/Share-based payment transactions and others | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.5 | Net profit for the accounting year/Others | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.6 | Net profit for the accounting year/Total share capital and capital reserve | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.7 | Net profit for the accounting year/Other comprehensive profit | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.8 | Net profit for the accounting year/Suplus/ deficit | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.9 | Net profit for the accounting year/Other capital items | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.10 | Net profit for the accounting year/Total Attributed to shareholders of the banking corporation | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.11 | Net profit for the accounting year/Non controlling interests | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 3.12 | Net profit for the accounting year/Total capital | boi_met:md106 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.1 | Dividend/Share capital | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.2 | Dividend/Receipts on account of shares and perpetual liabilities | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.3 | Dividend/Permium | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.4 | Dividend/Share-based payment transactions and others | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.5 | Dividend/Others | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.6 | Dividend/Total share capital and capital reserve | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.7 | Dividend/Other comprehensive profit | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.8 | Dividend/Suplus/ deficit | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.9 | Dividend/Other capital items | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.10 | Dividend/Total Attributed to shareholders of the banking corporation | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.11 | Dividend/Non controlling interests | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 4.12 | Dividend/Total capital | boi_met:md107 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.1 | Bonus granted to controlling shareholders/Share capital | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.2 | Bonus granted to controlling shareholders/Receipts on account of shares and perpetual liabilities | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.3 | Bonus granted to controlling shareholders/Permium | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.4 | Bonus granted to controlling shareholders/Share-based payment transactions and others | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.5 | Bonus granted to controlling shareholders/Others | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.6 | Bonus granted to controlling shareholders/Total share capital and capital reserve | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.7 | Bonus granted to controlling shareholders/Other comprehensive profit | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.8 | Bonus granted to controlling shareholders/Suplus/ deficit | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.9 | Bonus granted to controlling shareholders/Other capital items | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.10 | Bonus granted to controlling shareholders/Total Attributed to shareholders of the banking corporation | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.11 | Bonus granted to controlling shareholders/Non controlling interests | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 5.12 | Bonus granted to controlling shareholders/Total capital | boi_met:md108 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.1 | Issue of shares/Share capital | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.2 | Issue of shares/Receipts on account of shares and perpetual liabilities | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.3 | Issue of shares/Permium | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.4 | Issue of shares/Share-based payment transactions and others | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.5 | Issue of shares/Others | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.6 | Issue of shares/Total share capital and capital reserve | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.7 | Issue of shares/Other comprehensive profit | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.8 | Issue of shares/Suplus/ deficit | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.9 | Issue of shares/Other capital items | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.10 | Issue of shares/Total Attributed to shareholders of the banking corporation | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.11 | Issue of shares/Non controlling interests | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 6.12 | Issue of shares/Total capital | boi_met:md109 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.1 | Distribution of stock bonus/Share capital | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.2 | Distribution of stock bonus/Receipts on account of shares and perpetual liabilities | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.3 | Distribution of stock bonus/Permium | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.4 | Distribution of stock bonus/Share-based payment transactions and others | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.5 | Distribution of stock bonus/Others | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.6 | Distribution of stock bonus/Total share capital and capital reserve | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.7 | Distribution of stock bonus/Other comprehensive profit | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.8 | Distribution of stock bonus/Suplus/ deficit | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.9 | Distribution of stock bonus/Other capital items | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.10 | Distribution of stock bonus/Total Attributed to shareholders of the banking corporation | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.11 | Distribution of stock bonus/Non controlling interests | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 7.12 | Distribution of stock bonus/Total capital | boi_met:md110 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.1 | Conversion to convertible shares obligations/Share capital | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.2 | Conversion to convertible shares obligations/Receipts on account of shares and perpetual liabilities | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.3 | Conversion to convertible shares obligations/Permium | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.4 | Conversion to convertible shares obligations/Share-based payment transactions and others | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.5 | Conversion to convertible shares obligations/Others | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.6 | Conversion to convertible shares obligations/Total share capital and capital reserve | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.7 | Conversion to convertible shares obligations/Other comprehensive profit | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.8 | Conversion to convertible shares obligations/Suplus/ deficit | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.9 | Conversion to convertible shares obligations/Other capital items | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.10 | Conversion to convertible shares obligations/Total Attributed to shareholders of the banking corporation | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.11 | Conversion to convertible shares obligations/Non controlling interests | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 8.12 | Conversion to convertible shares obligations/Total capital | boi_met:md111 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.1 | Bonus from share-based payment transaction/Share capital | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.2 | Bonus from share-based payment transaction/Receipts on account of shares and perpetual liabilities | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.3 | Bonus from share-based payment transaction/Permium | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.4 | Bonus from share-based payment transaction/Share-based payment transactions and others | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.5 | Bonus from share-based payment transaction/Others | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.6 | Bonus from share-based payment transaction/Total share capital and capital reserve | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.7 | Bonus from share-based payment transaction/Other comprehensive profit | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.8 | Bonus from share-based payment transaction/Suplus/ deficit | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.9 | Bonus from share-based payment transaction/Other capital items | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.10 | Bonus from share-based payment transaction/Total Attributed to shareholders of the banking corporation | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.11 | Bonus from share-based payment transaction/Non controlling interests | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 9.12 | Bonus from share-based payment transaction/Total capital | boi_met:md112 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.1 | Bonus received from controlling shareholders/Share capital | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.2 | Bonus received from controlling shareholders/Receipts on account of shares and perpetual liabilities | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.3 | Bonus received from controlling shareholders/Permium | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.4 | Bonus received from controlling shareholders/Share-based payment transactions and others | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.5 | Bonus received from controlling shareholders/Others | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.6 | Bonus received from controlling shareholders/Total share capital and capital reserve | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.7 | Bonus received from controlling shareholders/Other comprehensive profit | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.8 | Bonus received from controlling shareholders/Suplus/ deficit | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.9 | Bonus received from controlling shareholders/Other capital items | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.10 | Bonus received from controlling shareholders/Total Attributed to shareholders of the banking corporation | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.11 | Bonus received from controlling shareholders/Non controlling interests | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 10.12 | Bonus received from controlling shareholders/Total capital | boi_met:md113 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x25 | N/A |
| 11.1 | Other comprehensive profit (loss) after taxes/Share capital | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.2 | Other comprehensive profit (loss) after taxes/Receipts on account of shares and perpetual liabilities | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.3 | Other comprehensive profit (loss) after taxes/Permium | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.4 | Other comprehensive profit (loss) after taxes/Share-based payment transactions and others | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.5 | Other comprehensive profit (loss) after taxes/Others | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.6 | Other comprehensive profit (loss) after taxes/Total share capital and capital reserve | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.7 | Other comprehensive profit (loss) after taxes/Other comprehensive profit | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.8 | Other comprehensive profit (loss) after taxes/Suplus/ deficit | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.9 | Other comprehensive profit (loss) after taxes/Other capital items | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.10 | Other comprehensive profit (loss) after taxes/Total Attributed to shareholders of the banking corporation | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.11 | Other comprehensive profit (loss) after taxes/Non controlling interests | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 11.12 | Other comprehensive profit (loss) after taxes/Total capital | boi_met:md114 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 | N/A |
| 12.1 | Balance as at 31 December/Share capital | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | N/A | N/A | boi_RP:x25 | N/A |
| 12.2 | Balance as at 31 December/Receipts on account of shares and perpetual liabilities | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | N/A | N/A | boi_RP:x25 | N/A |
| 12.3 | Balance as at 31 December/Permium | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | N/A | N/A | boi_RP:x25 | N/A |
| 12.4 | Balance as at 31 December/Share-based payment transactions and others | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | N/A | N/A | boi_RP:x25 | N/A |
| 12.5 | Balance as at 31 December/Others | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | N/A | N/A | boi_RP:x25 | N/A |
| 12.6 | Balance as at 31 December/Total share capital and capital reserve | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | N/A | N/A | boi_RP:x25 | N/A |
| 12.7 | Balance as at 31 December/Other comprehensive profit | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | N/A | N/A | boi_RP:x25 | N/A |
| 12.8 | Balance as at 31 December/Suplus/ deficit | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | N/A | N/A | boi_RP:x25 | N/A |
| 12.9 | Balance as at 31 December/Other capital items | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | N/A | N/A | boi_RP:x25 | N/A |
| 12.10 | Balance as at 31 December/Total Attributed to shareholders of the banking corporation | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |
| 12.11 | Balance as at 31 December/Non controlling interests | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |
| 12.12 | Balance as at 31 December/Total capital | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x25 | N/A |