| r0.1 | label_boi_a2/Receivables in respect of credit cards | | | | N/A | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x15 |
| r0.2 | label_boi_a2/Credit | | | | N/A | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x15 |
| r0.3 | label_boi_a2/Receivables in respect of credit cards | | | | N/A | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x4 |
| r0.4 | label_boi_a2/Credit | | | | N/A | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x4 |
| r0.5 | label_boi_a2/Credit risk guaranteed at banks and other | | | | N/A | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| r0.6 | label_boi_a2/Total | | | | N/A | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 1.1 | Balance of allowance for credit losses for beginning of year/Receivables in respect of credit cards | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | boi_RP:x8 | boi_SE:x15 |
| 1.2 | Balance of allowance for credit losses for beginning of year/Credit | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | boi_RP:x8 | boi_SE:x15 |
| 1.3 | Balance of allowance for credit losses for beginning of year/Receivables in respect of credit cards | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | boi_RP:x8 | boi_SE:x4 |
| 1.4 | Balance of allowance for credit losses for beginning of year/Credit | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | boi_RP:x8 | boi_SE:x4 |
| 1.5 | Balance of allowance for credit losses for beginning of year/Credit risk guaranteed at banks and other | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | boi_RP:x8 | N/A |
| 1.6 | Balance of allowance for credit losses for beginning of year/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | boi_RP:x8 | N/A |
| 2.1 | Expenses on credit losses/Receivables in respect of credit cards | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x15 |
| 2.2 | Expenses on credit losses/Credit | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x15 |
| 2.3 | Expenses on credit losses/Receivables in respect of credit cards | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x4 |
| 2.4 | Expenses on credit losses/Credit | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x4 |
| 2.5 | Expenses on credit losses/Credit risk guaranteed at banks and other | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 2.6 | Expenses on credit losses/Total | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 3.1 | Accounting write-offs/Receivables in respect of credit cards | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x15 |
| 3.2 | Accounting write-offs/Credit | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x15 |
| 3.3 | Accounting write-offs/Receivables in respect of credit cards | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x4 |
| 3.4 | Accounting write-offs/Credit | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x4 |
| 3.5 | Accounting write-offs/Credit risk guaranteed at banks and other | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 3.6 | Accounting write-offs/Total | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 4.1 | Collection of accounting written-off debts in previous years/Receivables in respect of credit cards | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x15 |
| 4.2 | Collection of accounting written-off debts in previous years/Credit | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x15 |
| 4.3 | Collection of accounting written-off debts in previous years/Receivables in respect of credit cards | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x4 |
| 4.4 | Collection of accounting written-off debts in previous years/Credit | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x4 |
| 4.5 | Collection of accounting written-off debts in previous years/Credit risk guaranteed at banks and other | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 4.6 | Collection of accounting written-off debts in previous years/Total | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 5.1 | Net accounting write-offs/Receivables in respect of credit cards | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x15 |
| 5.2 | Net accounting write-offs/Credit | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x15 |
| 5.3 | Net accounting write-offs/Receivables in respect of credit cards | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x4 |
| 5.4 | Net accounting write-offs/Credit | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x4 |
| 5.5 | Net accounting write-offs/Credit risk guaranteed at banks and other | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 5.6 | Net accounting write-offs/Total | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 6.1 | Other/Receivables in respect of credit cards | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x15 |
| 6.2 | Other/Credit | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x15 |
| 6.3 | Other/Receivables in respect of credit cards | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x4 |
| 6.4 | Other/Credit | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x4 |
| 6.5 | Other/Credit risk guaranteed at banks and other | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 6.6 | Other/Total | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 7.1 | Balance of allowance for credit losses for end of year/Receivables in respect of credit cards | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x15 |
| 7.2 | Balance of allowance for credit losses for end of year/Credit | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x15 |
| 7.3 | Balance of allowance for credit losses for end of year/Receivables in respect of credit cards | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x4 |
| 7.4 | Balance of allowance for credit losses for end of year/Credit | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x4 |
| 7.5 | Balance of allowance for credit losses for end of year/Credit risk guaranteed at banks and other | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 7.6 | Balance of allowance for credit losses for end of year/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x28 | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 8.1 | Of which: In respect of off-balance-sheet credit instruments/Receivables in respect of credit cards | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x15 |
| 8.2 | Of which: In respect of off-balance-sheet credit instruments/Credit | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x15 |
| 8.3 | Of which: In respect of off-balance-sheet credit instruments/Receivables in respect of credit cards | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x2 | boi_CS:x2 | boi_MC:x885 | boi_RP:x19 | N/A | boi_SE:x4 |
| 8.4 | Of which: In respect of off-balance-sheet credit instruments/Credit | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x2 | boi_CS:x2 | boi_MC:x886 | boi_RP:x19 | N/A | boi_SE:x4 |
| 8.5 | Of which: In respect of off-balance-sheet credit instruments/Credit risk guaranteed at banks and other | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x40 | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |
| 8.6 | Of which: In respect of off-balance-sheet credit instruments/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x8 | N/A | boi_CS:x2 | boi_MC:x878 | boi_RP:x19 | N/A | N/A |