| r0.1 | label_boi_a2/Quarter (Year -1) | | | | N/A | boi_CS:x2 | N/A | N/A | boi_PL:x69 | boi_RP:x19 |
| r0.2 | label_boi_a2/Quarter (Year -1) | | | | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| r0.3 | label_boi_a2/Year (-1) | | | | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| r1.1 | Defined benefit pension funds/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | N/A | boi_PL:x69 | boi_RP:x19 |
| r1.2 | Defined benefit pension funds/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| r1.3 | Defined benefit pension funds/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 1.1 | Service cost/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1008 | N/A | boi_PL:x69 | boi_RP:x19 |
| 1.2 | Service cost/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1008 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 1.3 | Service cost/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1008 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 2.1 | Interest cost/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1009 | N/A | boi_PL:x69 | boi_RP:x19 |
| 2.2 | Interest cost/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1009 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 2.3 | Interest cost/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1009 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 3.1 | Expected return on plan assets/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1010 | N/A | boi_PL:x69 | boi_RP:x19 |
| 3.2 | Expected return on plan assets/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1010 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 3.3 | Expected return on plan assets/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1010 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| r5.1 | Reduction by amounts not recognized/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | N/A | boi_PL:x69 | boi_RP:x19 |
| r5.2 | Reduction by amounts not recognized/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| r5.3 | Reduction by amounts not recognized/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 4.1 | Actuarial loss (gain), net/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1031 | N/A | boi_PL:x69 | boi_RP:x19 |
| 4.2 | Actuarial loss (gain), net/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1031 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 4.3 | Actuarial loss (gain), net/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1031 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 5.1 | Net liabilities in respect of transfer/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1032 | N/A | boi_PL:x69 | boi_RP:x19 |
| 5.2 | Net liabilities in respect of transfer/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1032 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 5.3 | Net liabilities in respect of transfer/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1032 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 6.1 | Cost of previous service/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1033 | N/A | boi_PL:x69 | boi_RP:x19 |
| 6.2 | Cost of previous service/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1033 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 6.3 | Cost of previous service/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1033 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 7.1 | Total reductions by amounts not recognized/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1011 | N/A | boi_PL:x69 | boi_RP:x19 |
| 7.2 | Total reductions by amounts not recognized/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1011 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 7.3 | Total reductions by amounts not recognized/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1011 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 8.1 | Other, including loss (gain) from reduction or removal/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1015 | N/A | boi_PL:x69 | boi_RP:x19 |
| 8.2 | Other, including loss (gain) from reduction or removal/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1015 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 8.3 | Other, including loss (gain) from reduction or removal/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1015 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 9.1 | Total cost of benefit, net/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1007 | N/A | boi_PL:x69 | boi_RP:x19 |
| 9.2 | Total cost of benefit, net/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1007 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 9.3 | Total cost of benefit, net/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1007 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 10.1 | Total expenditure in respect of defined contribution pension plans/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1006 | N/A | boi_PL:x69 | boi_RP:x19 |
| 10.2 | Total expenditure in respect of defined contribution pension plans/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1006 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 10.3 | Total expenditure in respect of defined contribution pension plans/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1006 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 11.1 | Total expenses included in salaries and related expenditures/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1005 | N/A | boi_PL:x69 | boi_RP:x19 |
| 11.2 | Total expenses included in salaries and related expenditures/Quarter (Year -1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1005 | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 11.3 | Total expenses included in salaries and related expenditures/Year (-1) | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_MC:x1005 | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |
| 12.1 | Deposits into defined benefit pension plans - deposits/Quarter (Year -1) | boi_met:md871 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | N/A | boi_PL:x69 | boi_RP:x19 |
| 12.2 | Deposits into defined benefit pension plans - deposits/Quarter (Year -1) | boi_met:md871 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_PL:x69 | boi_RP:x19 |
| 12.3 | Deposits into defined benefit pension plans - deposits/Year (-1) | boi_met:md871 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_PL:x69 | boi_RP:x24 |