| r0.1 | label_boi_a2/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | N/A | boi_MU:x1 | boi_RP:x25 |
| r0.2 | label_boi_a2/Company | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x25 |
| r1.1 | Income from businesses/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | N/A | boi_MU:x1 | boi_RP:x25 |
| r1.2 | Income from businesses/Company | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x25 |
| 1.1 | Business fees/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | N/A | boi_MC:x464 | boi_MU:x1 | boi_RP:x25 |
| 1.2 | Business fees/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | N/A | boi_MC:x464 | boi_MU:x1 | boi_RP:x25 |
| 2.1 | Other income/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | N/A | boi_MC:x465 | boi_MU:x1 | boi_RP:x25 |
| 2.2 | Other income/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | N/A | boi_MC:x465 | boi_MU:x1 | boi_RP:x25 |
| 3.1 | Total income from businesses - gross/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | N/A | boi_MC:x463 | boi_MU:x1 | boi_RP:x25 |
| 3.2 | Total income from businesses - gross/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | N/A | boi_MC:x463 | boi_MU:x1 | boi_RP:x25 |
| 4.1 | Less fees to other issuers1/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x2 | N/A | boi_MC:x466 | boi_MU:x1 | boi_RP:x25 |
| 4.2 | Less fees to other issuers1/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | boi_CS:x1 | N/A | boi_MC:x466 | boi_MU:x1 | boi_RP:x25 |
| 5.1 | Total income from businesses - net/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x462 | boi_MU:x1 | boi_RP:x25 |
| 5.2 | Total income from businesses - net/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x462 | boi_MU:x1 | boi_RP:x25 |
| r7.1 | Income on account of credit card holders/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | N/A | N/A | boi_MU:x1 | boi_RP:x25 |
| r7.2 | Income on account of credit card holders/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | N/A | N/A | boi_MU:x1 | boi_RP:x25 |
| 6.1 | Issuer fees/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | boi_GA:x1 | boi_MC:x468 | boi_MU:x1 | boi_RP:x25 |
| 6.2 | Issuer fees/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | boi_GA:x1 | boi_MC:x468 | boi_MU:x1 | boi_RP:x25 |
| 7.1 | Service fees/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | boi_GA:x1 | boi_MC:x469 | boi_MU:x1 | boi_RP:x25 |
| 7.2 | Service fees/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | boi_GA:x1 | boi_MC:x469 | boi_MU:x1 | boi_RP:x25 |
| 8.1 | Transactions abroad fees/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | boi_GA:x2 | boi_MC:x540 | boi_MU:x1 | boi_RP:x25 |
| 8.2 | Transactions abroad fees/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | boi_GA:x2 | boi_MC:x540 | boi_MU:x1 | boi_RP:x25 |
| 9.1 | Total income on account of credit card holders/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | N/A | boi_MC:x467 | boi_MU:x1 | boi_RP:x25 |
| 9.2 | Total income on account of credit card holders/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | N/A | boi_MC:x467 | boi_MU:x1 | boi_RP:x25 |
| 10.1 | Total income from credit card transactions/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x281 | boi_MU:x1 | boi_RP:x25 |
| 10.2 | Total income from credit card transactions/Company | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x281 | boi_MU:x1 | boi_RP:x25 |