| r0.1 | label_boi_a2/Opening balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | N/A | N/A | boi_PL:x40 | boi_RP:x24 | boi_RP:x22 |
| r0.2 | label_boi_a2/Realized profits (losses) | boi_met:mi901 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | N/A | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| r0.3 | label_boi_a2/Unrealized profits (losses) | boi_met:md701 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | N/A | boi_MU:x1 | boi_PL:x40 | boi_RP:x24 | N/A |
| r0.4 | label_boi_a2/Purchases, sales, and net settlements | boi_met:mi900 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | N/A | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| r0.5 | label_boi_a2/Transfers into/out of Tier 3 | boi_met:mi899 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | N/A | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| r0.6 | label_boi_a2/Closing balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | N/A | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 1.1 | Equities/Opening balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x30 | N/A | boi_PL:x40 | boi_RP:x24 | boi_RP:x22 |
| 1.2 | Equities/Realized profits (losses) | boi_met:mi901 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x30 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 1.3 | Equities/Unrealized profits (losses) | boi_met:md701 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x30 | boi_MU:x1 | boi_PL:x40 | boi_RP:x24 | N/A |
| 1.4 | Equities/Purchases, sales, and net settlements | boi_met:mi900 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x30 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 1.5 | Equities/Transfers into/out of Tier 3 | boi_met:mi899 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x30 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 1.6 | Equities/Closing balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x30 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 2.1 | Govt. bonds/Opening balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1025 | N/A | boi_PL:x40 | boi_RP:x24 | boi_RP:x22 |
| 2.2 | Govt. bonds/Realized profits (losses) | boi_met:mi901 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1025 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 2.3 | Govt. bonds/Unrealized profits (losses) | boi_met:md701 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1025 | boi_MU:x1 | boi_PL:x40 | boi_RP:x24 | N/A |
| 2.4 | Govt. bonds/Purchases, sales, and net settlements | boi_met:mi900 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1025 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 2.5 | Govt. bonds/Transfers into/out of Tier 3 | boi_met:mi899 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1025 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 2.6 | Govt. bonds/Closing balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1025 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 3.1 | Corporate bonds/Opening balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1026 | N/A | boi_PL:x40 | boi_RP:x24 | boi_RP:x22 |
| 3.2 | Corporate bonds/Realized profits (losses) | boi_met:mi901 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1026 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 3.3 | Corporate bonds/Unrealized profits (losses) | boi_met:md701 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1026 | boi_MU:x1 | boi_PL:x40 | boi_RP:x24 | N/A |
| 3.4 | Corporate bonds/Purchases, sales, and net settlements | boi_met:mi900 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1026 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 3.5 | Corporate bonds/Transfers into/out of Tier 3 | boi_met:mi899 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1026 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 3.6 | Corporate bonds/Closing balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1026 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 4.1 | Total bonds/Opening balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x15 | N/A | boi_PL:x40 | boi_RP:x24 | boi_RP:x22 |
| 4.2 | Total bonds/Realized profits (losses) | boi_met:mi901 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x15 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 4.3 | Total bonds/Unrealized profits (losses) | boi_met:md701 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x15 | boi_MU:x1 | boi_PL:x40 | boi_RP:x24 | N/A |
| 4.4 | Total bonds/Purchases, sales, and net settlements | boi_met:mi900 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x15 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 4.5 | Total bonds/Transfers into/out of Tier 3 | boi_met:mi899 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x15 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 4.6 | Total bonds/Closing balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x15 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 5.1 | Other/Opening balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1027 | N/A | boi_PL:x40 | boi_RP:x24 | boi_RP:x22 |
| 5.2 | Other/Realized profits (losses) | boi_met:mi901 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1027 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 5.3 | Other/Unrealized profits (losses) | boi_met:md701 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1027 | boi_MU:x1 | boi_PL:x40 | boi_RP:x24 | N/A |
| 5.4 | Other/Purchases, sales, and net settlements | boi_met:mi900 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1027 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 5.5 | Other/Transfers into/out of Tier 3 | boi_met:mi899 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1027 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 5.6 | Other/Closing balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1027 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 6.1 | Total/Opening balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1028 | N/A | boi_PL:x40 | boi_RP:x24 | boi_RP:x22 |
| 6.2 | Total/Realized profits (losses) | boi_met:mi901 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1028 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 6.3 | Total/Unrealized profits (losses) | boi_met:md701 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1028 | boi_MU:x1 | boi_PL:x40 | boi_RP:x24 | N/A |
| 6.4 | Total/Purchases, sales, and net settlements | boi_met:mi900 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1028 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 6.5 | Total/Transfers into/out of Tier 3 | boi_met:mi899 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1028 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |
| 6.6 | Total/Closing balance | boi_met:mi5 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_MC:x1024 | boi_MC:x1028 | N/A | boi_PL:x40 | boi_RP:x24 | N/A |