| r0.1 | label_boi_a2/Individual | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x6 |
| r0.2 | label_boi_a2/Extent of arrears | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x96 |
| r0.3 | label_boi_a2/Other | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x151 |
| r0.4 | label_boi_a2/Total | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r1.1 | Balance sheet credit to the public/Individual | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x6 |
| r1.2 | Balance sheet credit to the public/Extent of arrears | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x96 |
| r1.3 | Balance sheet credit to the public/Other | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x151 |
| r1.4 | Balance sheet credit to the public/Total | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.1 | Balance of allowance for credit losses as of beginning of year/Individual | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x16 | boi_ST:x6 |
| 1.2 | Balance of allowance for credit losses as of beginning of year/Extent of arrears | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x16 | boi_ST:x96 |
| 1.3 | Balance of allowance for credit losses as of beginning of year/Other | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x16 | boi_ST:x151 |
| 1.4 | Balance of allowance for credit losses as of beginning of year/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | boi_RP:x24 | boi_SE:x16 | N/A |
| r3.1 | Provision in respect of loan losses attributed to Profit and Loss/Individual | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| r3.2 | Provision in respect of loan losses attributed to Profit and Loss/Extent of arrears | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| r3.3 | Provision in respect of loan losses attributed to Profit and Loss/Other | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| r3.4 | Provision in respect of loan losses attributed to Profit and Loss/Total | | | | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 2.1 | Increase (decrease) in group allowance for credit losses/Individual | boi_met:md531 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 2.2 | Increase (decrease) in group allowance for credit losses/Extent of arrears | boi_met:md531 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 2.3 | Increase (decrease) in group allowance for credit losses/Other | boi_met:md531 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 2.4 | Increase (decrease) in group allowance for credit losses/Total | boi_met:md531 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 3.1 | Individual provisions for credit losses, gross/Individual | boi_met:md532 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 3.2 | Individual provisions for credit losses, gross/Extent of arrears | boi_met:md532 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 3.3 | Individual provisions for credit losses, gross/Other | boi_met:md532 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 3.4 | Individual provisions for credit losses, gross/Total | boi_met:md532 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 4.1 | Decrease in individual allowance for credit losses recorded in previous years/Individual | boi_met:md533 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 4.2 | Decrease in individual allowance for credit losses recorded in previous years/Extent of arrears | boi_met:md533 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 4.3 | Decrease in individual allowance for credit losses recorded in previous years/Other | boi_met:md533 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 4.4 | Decrease in individual allowance for credit losses recorded in previous years/Total | boi_met:md533 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 5.1 | Writeoffs/Individual | boi_met:md534 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 5.2 | Writeoffs/Extent of arrears | boi_met:md534 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 5.3 | Writeoffs/Other | boi_met:md534 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 5.4 | Writeoffs/Total | boi_met:md534 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 6.1 | Collection of debts written off in previous years/Individual | boi_met:md535 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 6.2 | Collection of debts written off in previous years/Extent of arrears | boi_met:md535 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 6.3 | Collection of debts written off in previous years/Other | boi_met:md535 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 6.4 | Collection of debts written off in previous years/Total | boi_met:md535 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 7.1 | Total/Individual | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 7.2 | Total/Extent of arrears | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 7.3 | Total/Other | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 7.4 | Total/Total | boi_met:md191 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 8.1 | Writeoffs/Individual | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 8.2 | Writeoffs/Extent of arrears | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 8.3 | Writeoffs/Other | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 8.4 | Writeoffs/Total | boi_met:md193 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 9.1 | Collection of debts written off in previous years/Individual | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 9.2 | Collection of debts written off in previous years/Extent of arrears | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 9.3 | Collection of debts written off in previous years/Other | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 9.4 | Collection of debts written off in previous years/Total | boi_met:md192 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 10.1 | Net accounts written off/Individual | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 10.2 | Net accounts written off/Extent of arrears | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 10.3 | Net accounts written off/Other | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 10.4 | Net accounts written off/Total | boi_met:md285 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 11.1 | Other/Individual | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x6 |
| 11.2 | Other/Extent of arrears | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x96 |
| 11.3 | Other/Other | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | boi_ST:x151 |
| 11.4 | Other/Total | boi_met:md197 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | boi_MU:x1 | N/A | boi_SE:x16 | N/A |
| 12.1 | Balance of allowance for credit losses as of end of quarter/Individual | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x6 |
| 12.2 | Balance of allowance for credit losses as of end of quarter/Extent of arrears | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x96 |
| 12.3 | Balance of allowance for credit losses as of end of quarter/Other | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_ST:x151 |
| 12.4 | Balance of allowance for credit losses as of end of quarter/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |