| r0.1 | label_boi_a2/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x25 | N/A |
| r0.2 | label_boi_a2/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x25 | N/A |
| r1.1 | In respect of assets:/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x25 | N/A |
| r1.2 | In respect of assets:/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x25 | N/A |
| 1.1 | Credit to the public/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x25 | boi_SE:x16 |
| 1.2 | Credit to the public/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x25 | boi_SE:x16 |
| 2.1 | Deposits in banks/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x25 | boi_SE:x1 |
| 2.2 | Deposits in banks/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | boi_MC:x8 | boi_MU:x1 | boi_RP:x25 | boi_SE:x1 |
| 3.1 | Securities borrowed or purchased under resell agreements/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | boi_MC:x28 | boi_MU:x1 | boi_RP:x25 | N/A |
| 3.2 | Securities borrowed or purchased under resell agreements/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | boi_MC:x28 | boi_MU:x1 | boi_RP:x25 | N/A |
| 4.1 | From other assets/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | boi_MC:x845 | boi_MU:x1 | boi_RP:x25 | N/A |
| 4.2 | From other assets/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | boi_MC:x845 | boi_MU:x1 | boi_RP:x25 | N/A |
| r6.1 | In respect of liabilities:/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x25 | N/A |
| r6.2 | In respect of liabilities:/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x25 | N/A |
| 5.1 | Deposits of the public/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x25 | boi_SE:x16 |
| 5.2 | Deposits of the public/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x25 | boi_SE:x16 |
| 6.1 | Deposits from banks/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x25 | boi_SE:x1 |
| 6.2 | Deposits from banks/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | boi_MC:x17 | boi_MU:x1 | boi_RP:x25 | boi_SE:x1 |
| 7.1 | Securities borrowed or purchased under resell agreements/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | boi_MC:x28 | boi_MU:x1 | boi_RP:x25 | N/A |
| 7.2 | Securities borrowed or purchased under resell agreements/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | boi_MC:x28 | boi_MU:x1 | boi_RP:x25 | N/A |
| 8.1 | Other liabilities/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | boi_MC:x913 | boi_MU:x1 | boi_RP:x25 | N/A |
| 8.2 | Other liabilities/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | boi_MC:x913 | boi_MU:x1 | boi_RP:x25 | N/A |
| 9.1 | Total interest income, net/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x1 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x25 | N/A |
| 9.2 | Total interest income, net/Of which: Affiliates companies | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_IP:x23 | boi_MC:x125 | N/A | boi_MU:x1 | boi_RP:x25 | N/A |