| r0.1 | label_boi_a2/Paid-up share capital | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | N/A | N/A | boi_RP:x24 | N/A |
| r0.2 | label_boi_a2/Receipts on account of perpetuity shares and liabilities | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | N/A | N/A | boi_RP:x24 | N/A |
| r0.3 | label_boi_a2/From premium | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | N/A | N/A | boi_RP:x24 | N/A |
| r0.4 | label_boi_a2/From benefit due to share-based payment | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | N/A | N/A | boi_RP:x24 | 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:x24 | N/A |
| r0.6 | label_boi_a2/Total paid-up share capital and capital funds | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | N/A | N/A | boi_RP:x24 | N/A |
| r0.7 | label_boi_a2/Accrued other profit | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | N/A | N/A | boi_RP:x24 | N/A |
| r0.8 | label_boi_a2/Surplus (Deficit) | | | | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | N/A | N/A | boi_RP:x24 | 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:x24 | N/A |
| r0.10 | label_boi_a2/non-controlling interests | | | | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x24 | N/A |
| r0.11 | label_boi_a2/Total equity capital | | | | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x24 | N/A |
| 1.1 | Balance at start of period/Paid-up 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:x24 | boi_RP:x22 |
| 1.2 | Balance at start of period/Receipts on account of perpetuity shares and 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:x24 | boi_RP:x22 |
| 1.3 | Balance at start of period/From premium | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | N/A | N/A | boi_RP:x24 | boi_RP:x22 |
| 1.4 | Balance at start of period/From benefit due to share-based payment | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | N/A | N/A | boi_RP:x24 | boi_RP:x22 |
| 1.5 | Balance at start of period/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:x24 | boi_RP:x22 |
| 1.6 | Balance at start of period/Total paid-up share capital and capital funds | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | N/A | N/A | boi_RP:x24 | boi_RP:x22 |
| 1.7 | Balance at start of period/Accrued other 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:x24 | boi_RP:x22 |
| 1.8 | Balance at start of period/Surplus (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:x24 | boi_RP:x22 |
| 1.9 | Balance at start of period/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:x24 | boi_RP:x22 |
| 1.10 | Balance at start of period/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:x24 | boi_RP:x22 |
| 1.11 | Balance at start of period/Total equity capital | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x24 | boi_RP:x22 |
| 2.1 | Net profit in period/Paid-up 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:x24 | N/A |
| 2.2 | Net profit in period/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 2.3 | Net profit in period/From premium | 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:x24 | N/A |
| 2.4 | Net profit in period/From benefit due to share-based payment | 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:x24 | N/A |
| 2.5 | Net profit in period/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:x24 | N/A |
| 2.6 | Net profit in period/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 2.7 | Net profit in period/Accrued other 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:x24 | N/A |
| 2.8 | Net profit in period/Surplus (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:x24 | N/A |
| 2.9 | Net profit in period/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:x24 | N/A |
| 2.10 | Net profit in period/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:x24 | N/A |
| 2.11 | Net profit in period/Total equity 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:x24 | N/A |
| 3.1 | Dividend/Paid-up 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:x24 | N/A |
| 3.2 | Dividend/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 3.3 | Dividend/From premium | 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:x24 | N/A |
| 3.4 | Dividend/From benefit due to share-based payment | 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:x24 | N/A |
| 3.5 | 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:x24 | N/A |
| 3.6 | Dividend/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 3.7 | Dividend/Accrued other 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:x24 | N/A |
| 3.8 | Dividend/Surplus (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:x24 | N/A |
| 3.9 | 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:x24 | N/A |
| 3.10 | 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:x24 | N/A |
| 3.11 | Dividend/Total equity 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:x24 | N/A |
| 4.1 | Benefits granted to controlling owner/Paid-up 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:x24 | N/A |
| 4.2 | Benefits granted to controlling owner/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 4.3 | Benefits granted to controlling owner/From premium | 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:x24 | N/A |
| 4.4 | Benefits granted to controlling owner/From benefit due to share-based payment | 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:x24 | N/A |
| 4.5 | Benefits granted to controlling owner/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:x24 | N/A |
| 4.6 | Benefits granted to controlling owner/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 4.7 | Benefits granted to controlling owner/Accrued other 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:x24 | N/A |
| 4.8 | Benefits granted to controlling owner/Surplus (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:x24 | N/A |
| 4.9 | Benefits granted to controlling owner/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:x24 | N/A |
| 4.10 | Benefits granted to controlling owner/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:x24 | N/A |
| 4.11 | Benefits granted to controlling owner/Total equity 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:x24 | N/A |
| 5.1 | Reconciliations and changes deriving: Issue of shares/Paid-up 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:x24 | N/A |
| 5.2 | Reconciliations and changes deriving: Issue of shares/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 5.3 | Reconciliations and changes deriving: Issue of shares/From premium | 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:x24 | N/A |
| 5.4 | Reconciliations and changes deriving: Issue of shares/From benefit due to share-based payment | 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:x24 | N/A |
| 5.5 | Reconciliations and changes deriving: 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:x24 | N/A |
| 5.6 | Reconciliations and changes deriving: Issue of shares/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 5.7 | Reconciliations and changes deriving: Issue of shares/Accrued other 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:x24 | N/A |
| 5.8 | Reconciliations and changes deriving: Issue of shares/Surplus (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:x24 | N/A |
| 5.9 | Reconciliations and changes deriving: 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:x24 | N/A |
| 5.10 | Reconciliations and changes deriving: 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:x24 | N/A |
| 5.11 | Reconciliations and changes deriving: Issue of shares/Total equity 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:x24 | N/A |
| 6.1 | Distribution of bonus shares/Paid-up 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:x24 | N/A |
| 6.2 | Distribution of bonus shares/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 6.3 | Distribution of bonus shares/From premium | 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:x24 | N/A |
| 6.4 | Distribution of bonus shares/From benefit due to share-based payment | 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:x24 | N/A |
| 6.5 | Distribution of bonus shares/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:x24 | N/A |
| 6.6 | Distribution of bonus shares/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 6.7 | Distribution of bonus shares/Accrued other 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:x24 | N/A |
| 6.8 | Distribution of bonus shares/Surplus (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:x24 | N/A |
| 6.9 | Distribution of bonus shares/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:x24 | N/A |
| 6.10 | Distribution of bonus shares/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:x24 | N/A |
| 6.11 | Distribution of bonus shares/Total equity 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:x24 | N/A |
| 7.1 | Conversion to shares of convertible liabilities/Paid-up 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:x24 | N/A |
| 7.2 | Conversion to shares of convertible liabilities/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 7.3 | Conversion to shares of convertible liabilities/From premium | 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:x24 | N/A |
| 7.4 | Conversion to shares of convertible liabilities/From benefit due to share-based payment | 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:x24 | N/A |
| 7.5 | Conversion to shares of convertible liabilities/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:x24 | N/A |
| 7.6 | Conversion to shares of convertible liabilities/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 7.7 | Conversion to shares of convertible liabilities/Accrued other 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:x24 | N/A |
| 7.8 | Conversion to shares of convertible liabilities/Surplus (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:x24 | N/A |
| 7.9 | Conversion to shares of convertible liabilities/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:x24 | N/A |
| 7.10 | Conversion to shares of convertible liabilities/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:x24 | N/A |
| 7.11 | Conversion to shares of convertible liabilities/Total equity 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:x24 | N/A |
| 8.1 | Benefit due to share-based payment transactions/Paid-up 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:x24 | N/A |
| 8.2 | Benefit due to share-based payment transactions/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 8.3 | Benefit due to share-based payment transactions/From premium | 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:x24 | N/A |
| 8.4 | Benefit due to share-based payment transactions/From benefit due to share-based payment | 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:x24 | N/A |
| 8.5 | Benefit due to share-based payment transactions/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:x24 | N/A |
| 8.6 | Benefit due to share-based payment transactions/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 8.7 | Benefit due to share-based payment transactions/Accrued other 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:x24 | N/A |
| 8.8 | Benefit due to share-based payment transactions/Surplus (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:x24 | N/A |
| 8.9 | Benefit due to share-based payment transactions/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:x24 | N/A |
| 8.10 | Benefit due to share-based payment transactions/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:x24 | N/A |
| 8.11 | Benefit due to share-based payment transactions/Total equity 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:x24 | N/A |
| 9.1 | Benefits received from controlling owner/Paid-up 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:x24 | N/A |
| 9.2 | Benefits received from controlling owner/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 9.3 | Benefits received from controlling owner/From premium | 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:x24 | N/A |
| 9.4 | Benefits received from controlling owner/From benefit due to share-based payment | 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:x24 | N/A |
| 9.5 | Benefits received from controlling owner/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:x24 | N/A |
| 9.6 | Benefits received from controlling owner/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 9.7 | Benefits received from controlling owner/Accrued other 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:x24 | N/A |
| 9.8 | Benefits received from controlling owner/Surplus (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:x24 | N/A |
| 9.9 | Benefits received from controlling owner/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:x24 | N/A |
| 9.10 | Benefits received from controlling owner/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:x24 | N/A |
| 9.11 | Benefits received from controlling owner/Total equity 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:x24 | N/A |
| 10.1 | Other overall profit (loss), net after tax effect/Paid-up 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:x24 | N/A |
| 10.2 | Other overall profit (loss), net after tax effect/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 10.3 | Other overall profit (loss), net after tax effect/From premium | 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:x24 | N/A |
| 10.4 | Other overall profit (loss), net after tax effect/From benefit due to share-based payment | 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:x24 | N/A |
| 10.5 | Other overall profit (loss), net after tax effect/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:x24 | N/A |
| 10.6 | Other overall profit (loss), net after tax effect/Total paid-up share capital and capital funds | 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:x24 | N/A |
| 10.7 | Other overall profit (loss), net after tax effect/Accrued other 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:x24 | N/A |
| 10.8 | Other overall profit (loss), net after tax effect/Surplus (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:x24 | N/A |
| 10.9 | Other overall profit (loss), net after tax effect/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:x24 | N/A |
| 10.10 | Other overall profit (loss), net after tax effect/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:x24 | N/A |
| 10.11 | Other overall profit (loss), net after tax effect/Total equity 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:x24 | N/A |
| 11.1 | Other reconciliations/Paid-up share capital | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x405 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.2 | Other reconciliations/Receipts on account of perpetuity shares and liabilities | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x404 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.3 | Other reconciliations/From premium | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.4 | Other reconciliations/From benefit due to share-based payment | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.5 | Other reconciliations/Others | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x401 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.6 | Other reconciliations/Total paid-up share capital and capital funds | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.7 | Other reconciliations/Accrued other profit | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.8 | Other reconciliations/Surplus (Deficit) | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x398 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.9 | Other reconciliations/Other capital items | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x397 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.10 | Other reconciliations/non-controlling interests | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x2 | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 11.11 | Other reconciliations/Total equity capital | boi_met:mi120 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | boi_MU:x1 | N/A | boi_RP:x24 | N/A |
| 12.1 | Balance at end of period/Paid-up 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:x24 | N/A |
| 12.2 | Balance at end of period/Receipts on account of perpetuity shares and 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:x24 | N/A |
| 12.3 | Balance at end of period/From premium | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x403 | N/A | N/A | boi_RP:x24 | N/A |
| 12.4 | Balance at end of period/From benefit due to share-based payment | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x402 | N/A | N/A | boi_RP:x24 | N/A |
| 12.5 | Balance at end of period/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:x24 | N/A |
| 12.6 | Balance at end of period/Total paid-up share capital and capital funds | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | boi_CN:x1 | boi_CS:x2 | boi_MC:x400 | N/A | N/A | boi_RP:x24 | N/A |
| 12.7 | Balance at end of period/Accrued other 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:x24 | N/A |
| 12.8 | Balance at end of period/Surplus (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:x24 | N/A |
| 12.9 | Balance at end of period/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:x24 | N/A |
| 12.10 | Balance at end of period/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:x24 | N/A |
| 12.11 | Balance at end of period/Total equity capital | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x3 | N/A | boi_CS:x2 | boi_MC:x2 | N/A | N/A | boi_RP:x24 | N/A |