| r0.1 | label_boi_a2/Commercial | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_SE:x4 |
| r0.2 | label_boi_a2/Housing | | | | N/A | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_SE:x15 |
| r0.3 | label_boi_a2/Other private | | | | N/A | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_SE:x15 |
| r0.4 | label_boi_a2/Total | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_SE:x16 |
| r0.5 | label_boi_a2/Banks and governments | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | boi_SE:x77 |
| r0.6 | label_boi_a2/Total | | | | N/A | N/A | boi_CS:x2 | boi_GA:x1 | N/A | N/A | N/A | N/A |
| r0.7 | label_boi_a2/Commercial | | | | N/A | N/A | boi_CS:x2 | boi_GA:x2 | N/A | N/A | N/A | boi_SE:x4 |
| r0.8 | label_boi_a2/Housing | | | | N/A | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | N/A | N/A | N/A | boi_SE:x15 |
| r0.9 | label_boi_a2/Other private | | | | N/A | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | N/A | N/A | N/A | boi_SE:x15 |
| r0.10 | label_boi_a2/Total | | | | N/A | N/A | boi_CS:x2 | boi_GA:x2 | N/A | N/A | N/A | boi_SE:x16 |
| r0.11 | label_boi_a2/Banks and governments | | | | N/A | N/A | boi_CS:x2 | boi_GA:x2 | N/A | N/A | N/A | boi_SE:x77 |
| r0.12 | label_boi_a2/Total | | | | N/A | N/A | boi_CS:x2 | boi_GA:x2 | N/A | N/A | N/A | N/A |
| r1.1 | Change in balance of credit loss provision/Commercial | | | | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x4 |
| r1.2 | Change in balance of credit loss provision/Housing | | | | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x15 |
| r1.3 | Change in balance of credit loss provision/Other private | | | | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x15 |
| r1.4 | Change in balance of credit loss provision/Total | | | | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x16 |
| r1.5 | Change in balance of credit loss provision/Banks and governments | | | | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x77 |
| r1.6 | Change in balance of credit loss provision/Total | | | | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | N/A |
| r1.7 | Change in balance of credit loss provision/Commercial | | | | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x4 |
| r1.8 | Change in balance of credit loss provision/Housing | | | | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x15 |
| r1.9 | Change in balance of credit loss provision/Other private | | | | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x15 |
| r1.10 | Change in balance of credit loss provision/Total | | | | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x16 |
| r1.11 | Change in balance of credit loss provision/Banks and governments | | | | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x77 |
| r1.12 | Change in balance of credit loss provision/Total | | | | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | N/A |
| 1.1 | Balance of credit loss provision at beginning of period/Commercial | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x4 |
| 1.2 | Balance of credit loss provision at beginning of period/Housing | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x15 |
| 1.3 | Balance of credit loss provision at beginning of period/Other private | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x15 |
| 1.4 | Balance of credit loss provision at beginning of period/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x16 |
| 1.5 | Balance of credit loss provision at beginning of period/Banks and governments | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x77 |
| 1.6 | Balance of credit loss provision at beginning of period/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | boi_RP:x22 | N/A |
| 1.7 | Balance of credit loss provision at beginning of period/Commercial | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x4 |
| 1.8 | Balance of credit loss provision at beginning of period/Housing | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x15 |
| 1.9 | Balance of credit loss provision at beginning of period/Other private | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x15 |
| 1.10 | Balance of credit loss provision at beginning of period/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x16 |
| 1.11 | Balance of credit loss provision at beginning of period/Banks and governments | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | boi_RP:x22 | boi_SE:x77 |
| 1.12 | Balance of credit loss provision at beginning of period/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | boi_RP:x22 | N/A |
| 2.1 | Credit loss expenses/Commercial | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 2.2 | Credit loss expenses/Housing | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 2.3 | Credit loss expenses/Other private | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 2.4 | Credit loss expenses/Total | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 2.5 | Credit loss expenses/Banks and governments | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 2.6 | Credit loss expenses/Total | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 2.7 | Credit loss expenses/Commercial | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 2.8 | Credit loss expenses/Housing | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 2.9 | Credit loss expenses/Other private | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 2.10 | Credit loss expenses/Total | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 2.11 | Credit loss expenses/Banks and governments | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 2.12 | Credit loss expenses/Total | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 3.1 | Write-off of mortgage loans/Commercial | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 3.2 | Write-off of mortgage loans/Housing | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 3.3 | Write-off of mortgage loans/Other private | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 3.4 | Write-off of mortgage loans/Total | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 3.5 | Write-off of mortgage loans/Banks and governments | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 3.6 | Write-off of mortgage loans/Total | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 3.7 | Write-off of mortgage loans/Commercial | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 3.8 | Write-off of mortgage loans/Housing | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 3.9 | Write-off of mortgage loans/Other private | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 3.10 | Write-off of mortgage loans/Total | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 3.11 | Write-off of mortgage loans/Banks and governments | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 3.12 | Write-off of mortgage loans/Total | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 4.1 | Collection of debts written off books in previous years/Commercial | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 4.2 | Collection of debts written off books in previous years/Housing | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 4.3 | Collection of debts written off books in previous years/Other private | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 4.4 | Collection of debts written off books in previous years/Total | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 4.5 | Collection of debts written off books in previous years/Banks and governments | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 4.6 | Collection of debts written off books in previous years/Total | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 4.7 | Collection of debts written off books in previous years/Commercial | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 4.8 | Collection of debts written off books in previous years/Housing | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 4.9 | Collection of debts written off books in previous years/Other private | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 4.10 | Collection of debts written off books in previous years/Total | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 4.11 | Collection of debts written off books in previous years/Banks and governments | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 4.12 | Collection of debts written off books in previous years/Total | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 5.1 | Net accounting write-offs/Commercial | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 5.2 | Net accounting write-offs/Housing | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 5.3 | Net accounting write-offs/Other private | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 5.4 | Net accounting write-offs/Total | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 5.5 | Net accounting write-offs/Banks and governments | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 5.6 | Net accounting write-offs/Total | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 5.7 | Net accounting write-offs/Commercial | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 5.8 | Net accounting write-offs/Housing | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 5.9 | Net accounting write-offs/Other private | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 5.10 | Net accounting write-offs/Total | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 5.11 | Net accounting write-offs/Banks and governments | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 5.12 | Net accounting write-offs/Total | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 6.1 | Adjustments from translation of financial statements/Commercial | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 6.2 | Adjustments from translation of financial statements/Housing | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 6.3 | Adjustments from translation of financial statements/Other private | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 6.4 | Adjustments from translation of financial statements/Total | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 6.5 | Adjustments from translation of financial statements/Banks and governments | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 6.6 | Adjustments from translation of financial statements/Total | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 6.7 | Adjustments from translation of financial statements/Commercial | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 6.8 | Adjustments from translation of financial statements/Housing | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 6.9 | Adjustments from translation of financial statements/Other private | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 6.10 | Adjustments from translation of financial statements/Total | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 6.11 | Adjustments from translation of financial statements/Banks and governments | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 6.12 | Adjustments from translation of financial statements/Total | boi_met:md194 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 7.1 | Other/Commercial | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 7.2 | Other/Housing | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 7.3 | Other/Other private | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 7.4 | Other/Total | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 7.5 | Other/Banks and governments | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 7.6 | Other/Total | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 7.7 | Other/Commercial | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x4 |
| 7.8 | Other/Housing | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 7.9 | Other/Other private | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x15 |
| 7.10 | Other/Total | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x16 |
| 7.11 | Other/Banks and governments | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | boi_SE:x77 |
| 7.12 | Other/Total | boi_met:md195 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | boi_MU:x1 | N/A | N/A |
| 8.1 | Balance of credit loss provision at end of period/Commercial | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x4 |
| 8.2 | Balance of credit loss provision at end of period/Housing | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x15 |
| 8.3 | Balance of credit loss provision at end of period/Other private | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x15 |
| 8.4 | Balance of credit loss provision at end of period/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x16 |
| 8.5 | Balance of credit loss provision at end of period/Banks and governments | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | boi_SE:x77 |
| 8.6 | Balance of credit loss provision at end of period/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x878 | N/A | N/A | N/A |
| 8.7 | Balance of credit loss provision at end of period/Commercial | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x4 |
| 8.8 | Balance of credit loss provision at end of period/Housing | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x15 |
| 8.9 | Balance of credit loss provision at end of period/Other private | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x15 |
| 8.10 | Balance of credit loss provision at end of period/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x16 |
| 8.11 | Balance of credit loss provision at end of period/Banks and governments | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | boi_SE:x77 |
| 8.12 | Balance of credit loss provision at end of period/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x878 | N/A | N/A | N/A |
| 9.1 | Thereof: on account of off-balance-sheet credit instruments/Commercial | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x879 | N/A | N/A | boi_SE:x4 |
| 9.2 | Thereof: on account of off-balance-sheet credit instruments/Housing | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x35 | boi_CS:x2 | boi_GA:x1 | boi_MC:x879 | N/A | N/A | boi_SE:x15 |
| 9.3 | Thereof: on account of off-balance-sheet credit instruments/Other private | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x38 | boi_CS:x2 | boi_GA:x1 | boi_MC:x879 | N/A | N/A | boi_SE:x15 |
| 9.4 | Thereof: on account of off-balance-sheet credit instruments/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x879 | N/A | N/A | boi_SE:x16 |
| 9.5 | Thereof: on account of off-balance-sheet credit instruments/Banks and governments | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x879 | N/A | N/A | boi_SE:x77 |
| 9.6 | Thereof: on account of off-balance-sheet credit instruments/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_GA:x1 | boi_MC:x879 | N/A | N/A | N/A |
| 9.7 | Thereof: on account of off-balance-sheet credit instruments/Commercial | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x879 | N/A | N/A | boi_SE:x4 |
| 9.8 | Thereof: on account of off-balance-sheet credit instruments/Housing | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x35 | boi_CS:x2 | boi_GA:x2 | boi_MC:x879 | N/A | N/A | boi_SE:x15 |
| 9.9 | Thereof: on account of off-balance-sheet credit instruments/Other private | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x38 | boi_CS:x2 | boi_GA:x2 | boi_MC:x879 | N/A | N/A | boi_SE:x15 |
| 9.10 | Thereof: on account of off-balance-sheet credit instruments/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x879 | N/A | N/A | boi_SE:x16 |
| 9.11 | Thereof: on account of off-balance-sheet credit instruments/Banks and governments | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x879 | N/A | N/A | boi_SE:x77 |
| 9.12 | Thereof: on account of off-balance-sheet credit instruments/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_GA:x2 | boi_MC:x879 | N/A | N/A | N/A |