| r0.1 | label_boi_a2/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | N/A | boi_MU:x1 | boi_RP:x25 |
| r0.2 | label_boi_a2/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x25 |
| 1.1 | Salaries/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x162 | boi_MU:x1 | boi_RP:x25 |
| 1.2 | Salaries/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x162 | boi_MU:x1 | boi_RP:x25 |
| 2.1 | Expenses deriving from share based payments transactions*/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x163 | boi_MU:x1 | boi_RP:x25 |
| 2.2 | Expenses deriving from share based payments transactions*/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x163 | boi_MU:x1 | boi_RP:x25 |
| 3.1 | Accompanying expenses are other for many fund of perfecting vacation and disease/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x999 | boi_MU:x1 | boi_RP:x25 |
| 3.2 | Accompanying expenses are other for many fund of perfecting vacation and disease/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x999 | boi_MU:x1 | boi_RP:x25 |
| 4.1 | Long term bonuses/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x1029 | boi_MU:x1 | boi_RP:x25 |
| 4.2 | Long term bonuses/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x1029 | boi_MU:x1 | boi_RP:x25 |
| 5.1 | National insurance and VAT on salaries/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x167 | boi_MU:x1 | boi_RP:x25 |
| 5.2 | National insurance and VAT on salaries/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x167 | boi_MU:x1 | boi_RP:x25 |
| 6.1 | Expenses for pensions (include compensation and rewards) defined bonus/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x1007 | boi_MU:x1 | boi_RP:x25 |
| 6.2 | Expenses for pensions (include compensation and rewards) defined bonus/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x1007 | boi_MU:x1 | boi_RP:x25 |
| 7.1 | Expenses for pensions (include compensation and rewards) defined depositing/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x1006 | boi_MU:x1 | boi_RP:x25 |
| 7.2 | Expenses for pensions (include compensation and rewards) defined depositing/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x1006 | boi_MU:x1 | boi_RP:x25 |
| 8.1 | Other benefit after ending the employment and benefits after retire that are not pension/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x1000 | boi_MU:x1 | boi_RP:x25 |
| 8.2 | Other benefit after ending the employment and benefits after retire that are not pension/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x1000 | boi_MU:x1 | boi_RP:x25 |
| 9.1 | of which: Servicing cost for other benefit after ending the employment and benefits after retire that are not pension/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x1087 | boi_MU:x1 | boi_RP:x25 |
| 9.2 | of which: Servicing cost for other benefit after ending the employment and benefits after retire that are not pension/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x1087 | boi_MU:x1 | boi_RP:x25 |
| 10.1 | Special benefit for firing/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x1001 | boi_MU:x1 | boi_RP:x25 |
| 10.2 | Special benefit for firing/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x1001 | boi_MU:x1 | boi_RP:x25 |
| 11.1 | Expenses for other benefits for employers/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x1002 | boi_MU:x1 | boi_RP:x25 |
| 11.2 | Expenses for other benefits for employers/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x1002 | boi_MU:x1 | boi_RP:x25 |
| 12.1 | Early retirement/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x170 | boi_MU:x1 | boi_RP:x25 |
| 12.2 | Early retirement/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x170 | boi_MU:x1 | boi_RP:x25 |
| 13.1 | Total salaries and related expenses/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x161 | boi_MU:x1 | boi_RP:x25 |
| 13.2 | Total salaries and related expenses/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x161 | boi_MU:x1 | boi_RP:x25 |
| 14.1 | Of which: Salaries and related expenses abroad/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | boi_GA:x2 | boi_MC:x161 | boi_MU:x1 | boi_RP:x25 |
| 14.2 | Of which: Salaries and related expenses abroad/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | boi_GA:x2 | boi_MC:x161 | boi_MU:x1 | boi_RP:x25 |
| 15.1 | *Of which: Expenses deriving from share based payments transactions settled in capital instruments/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x164 | boi_MU:x1 | boi_RP:x25 |
| 15.2 | *Of which: Expenses deriving from share based payments transactions settled in capital instruments/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x164 | boi_MU:x1 | boi_RP:x25 |