| r0.1 | label_boi_a2/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.2 | label_boi_a2/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.3 | label_boi_a2/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.4 | label_boi_a2/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.5 | label_boi_a2/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.6 | label_boi_a2/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.7 | label_boi_a2/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.8 | label_boi_a2/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.9 | label_boi_a2/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | N/A | boi_SE:x16 | N/A |
| r0.10 | label_boi_a2/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.11 | label_boi_a2/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| r0.12 | label_boi_a2/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | N/A | boi_SE:x16 | N/A |
| 1.1 | Total/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.2 | Total/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.3 | Total/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.4 | Total/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.5 | Total/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.6 | Total/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.7 | Total/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.8 | Total/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.9 | Total/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | N/A | boi_SE:x16 | N/A |
| 1.10 | Total/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.11 | Total/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 1.12 | Total/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | N/A | boi_SE:x16 | N/A |
| 2.1 | Thereof: buying groups/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.2 | Thereof: buying groups/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.3 | Thereof: buying groups/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.4 | Thereof: buying groups/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.5 | Thereof: buying groups/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.6 | Thereof: buying groups/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.7 | Thereof: buying groups/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.8 | Thereof: buying groups/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.9 | Thereof: buying groups/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | N/A | boi_SE:x79 | N/A |
| 2.10 | Thereof: buying groups/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.11 | Thereof: buying groups/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x79 | N/A |
| 2.12 | Thereof: buying groups/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | N/A | boi_SE:x79 | N/A |
| 3.1 | Thereof: nonresidents/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.2 | Thereof: nonresidents/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.3 | Thereof: nonresidents/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.4 | Thereof: nonresidents/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.5 | Thereof: nonresidents/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.6 | Thereof: nonresidents/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.7 | Thereof: nonresidents/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.8 | Thereof: nonresidents/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.9 | Thereof: nonresidents/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x77 | N/A | N/A | boi_SE:x16 | N/A |
| 3.10 | Thereof: nonresidents/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.11 | Thereof: nonresidents/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x8 | N/A | N/A | boi_SE:x16 | N/A |
| 3.12 | Thereof: nonresidents/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x77 | N/A | N/A | boi_SE:x16 | N/A |
| 4.1 | Thereof: loans issued with grace/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.2 | Thereof: loans issued with grace/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.3 | Thereof: loans issued with grace/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.4 | Thereof: loans issued with grace/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.5 | Thereof: loans issued with grace/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.6 | Thereof: loans issued with grace/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.7 | Thereof: loans issued with grace/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.8 | Thereof: loans issued with grace/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.9 | Thereof: loans issued with grace/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.10 | Thereof: loans issued with grace/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.11 | Thereof: loans issued with grace/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 4.12 | Thereof: loans issued with grace/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | boi_PI:x31 | N/A | boi_SE:x16 | N/A |
| 5.1 | Thereof: Bullet and Baloon loans/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.2 | Thereof: Bullet and Baloon loans/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.3 | Thereof: Bullet and Baloon loans/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.4 | Thereof: Bullet and Baloon loans/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.5 | Thereof: Bullet and Baloon loans/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.6 | Thereof: Bullet and Baloon loans/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.7 | Thereof: Bullet and Baloon loans/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.8 | Thereof: Bullet and Baloon loans/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.9 | Thereof: Bullet and Baloon loans/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.10 | Thereof: Bullet and Baloon loans/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.11 | Thereof: Bullet and Baloon loans/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 5.12 | Thereof: Bullet and Baloon loans/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | boi_PI:x24 | N/A | boi_SE:x16 | N/A |
| 6.1 | Thereof: credit lines with assurance of interest rate/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.2 | Thereof: credit lines with assurance of interest rate/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.3 | Thereof: credit lines with assurance of interest rate/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.4 | Thereof: credit lines with assurance of interest rate/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.5 | Thereof: credit lines with assurance of interest rate/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.6 | Thereof: credit lines with assurance of interest rate/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.7 | Thereof: credit lines with assurance of interest rate/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.8 | Thereof: credit lines with assurance of interest rate/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.9 | Thereof: credit lines with assurance of interest rate/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.10 | Thereof: credit lines with assurance of interest rate/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.11 | Thereof: credit lines with assurance of interest rate/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 6.12 | Thereof: credit lines with assurance of interest rate/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | boi_PI:x50 | N/A | boi_SE:x16 | N/A |
| 7.1 | Balance of housing loans issued from April 1, 2011, onward/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.2 | Balance of housing loans issued from April 1, 2011, onward/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.3 | Balance of housing loans issued from April 1, 2011, onward/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.4 | Balance of housing loans issued from April 1, 2011, onward/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.5 | Balance of housing loans issued from April 1, 2011, onward/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.6 | Balance of housing loans issued from April 1, 2011, onward/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.7 | Balance of housing loans issued from April 1, 2011, onward/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.8 | Balance of housing loans issued from April 1, 2011, onward/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.9 | Balance of housing loans issued from April 1, 2011, onward/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.10 | Balance of housing loans issued from April 1, 2011, onward/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.11 | Balance of housing loans issued from April 1, 2011, onward/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 7.12 | Balance of housing loans issued from April 1, 2011, onward/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | N/A | boi_SE:x16 | boi_TI:x50 |
| 8.1 | Thereof: housing for investment/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.2 | Thereof: housing for investment/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x5 | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.3 | Thereof: housing for investment/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.4 | Thereof: housing for investment/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x6 | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.5 | Thereof: housing for investment/Fixed rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x23 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.6 | Thereof: housing for investment/Floating rate | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_CU:x24 | boi_CU:x15 | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.7 | Thereof: housing for investment/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.8 | Thereof: housing for investment/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.9 | Thereof: housing for investment/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x36 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.10 | Thereof: housing for investment/Loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.11 | Thereof: housing for investment/No. of loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x8 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |
| 8.12 | Thereof: housing for investment/Balance of credit lines | boi_met:mi204 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CL:x37 | boi_CS:x1 | N/A | N/A | N/A | boi_MC:x77 | N/A | boi_PU:x1 | boi_SE:x16 | boi_TI:x50 |