| r0.1 | label_boi_a2/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.2 | label_boi_a2/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.3 | label_boi_a2/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.4 | label_boi_a2/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.5 | label_boi_a2/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.6 | label_boi_a2/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.7 | label_boi_a2/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.8 | label_boi_a2/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.9 | label_boi_a2/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.10 | label_boi_a2/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.11 | label_boi_a2/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.12 | label_boi_a2/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.13 | label_boi_a2/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r0.14 | label_boi_a2/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.1 | A. Total of all exposures/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.2 | A. Total of all exposures/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.3 | A. Total of all exposures/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.4 | A. Total of all exposures/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.5 | A. Total of all exposures/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.6 | A. Total of all exposures/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.7 | A. Total of all exposures/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.8 | A. Total of all exposures/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.9 | A. Total of all exposures/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.10 | A. Total of all exposures/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.11 | A. Total of all exposures/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.12 | A. Total of all exposures/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.13 | A. Total of all exposures/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 1.14 | A. Total of all exposures/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.1 | Thereof: central banks/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.2 | Thereof: central banks/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.3 | Thereof: central banks/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.4 | Thereof: central banks/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.5 | Thereof: central banks/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.6 | Thereof: central banks/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.7 | Thereof: central banks/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.8 | Thereof: central banks/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.9 | Thereof: central banks/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.10 | Thereof: central banks/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.11 | Thereof: central banks/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.12 | Thereof: central banks/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.13 | Thereof: central banks/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 2.14 | Thereof: central banks/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x26 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.1 | B. Breakdown of exposures by exposure type/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.2 | B. Breakdown of exposures by exposure type/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.3 | B. Breakdown of exposures by exposure type/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.4 | B. Breakdown of exposures by exposure type/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.5 | B. Breakdown of exposures by exposure type/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.6 | B. Breakdown of exposures by exposure type/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.7 | B. Breakdown of exposures by exposure type/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.8 | B. Breakdown of exposures by exposure type/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.9 | B. Breakdown of exposures by exposure type/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.10 | B. Breakdown of exposures by exposure type/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.11 | B. Breakdown of exposures by exposure type/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.12 | B. Breakdown of exposures by exposure type/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.13 | B. Breakdown of exposures by exposure type/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r3.14 | B. Breakdown of exposures by exposure type/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.1 | Balance sheet exposures/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.2 | Balance sheet exposures/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.3 | Balance sheet exposures/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.4 | Balance sheet exposures/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.5 | Balance sheet exposures/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.6 | Balance sheet exposures/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.7 | Balance sheet exposures/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.8 | Balance sheet exposures/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.9 | Balance sheet exposures/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.10 | Balance sheet exposures/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.11 | Balance sheet exposures/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.12 | Balance sheet exposures/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.13 | Balance sheet exposures/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r4.14 | Balance sheet exposures/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.1 | Credit/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.2 | Credit/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.3 | Credit/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.4 | Credit/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.5 | Credit/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.6 | Credit/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.7 | Credit/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.8 | Credit/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.9 | Credit/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.10 | Credit/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.11 | Credit/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.12 | Credit/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.13 | Credit/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 3.14 | Credit/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x8 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.1 | Bonds/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.2 | Bonds/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.3 | Bonds/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.4 | Bonds/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.5 | Bonds/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.6 | Bonds/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.7 | Bonds/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.8 | Bonds/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.9 | Bonds/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.10 | Bonds/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.11 | Bonds/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.12 | Bonds/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.13 | Bonds/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 4.14 | Bonds/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x15 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.1 | Total for balance sheet/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.2 | Total for balance sheet/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.3 | Total for balance sheet/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.4 | Total for balance sheet/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.5 | Total for balance sheet/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.6 | Total for balance sheet/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.7 | Total for balance sheet/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.8 | Total for balance sheet/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.9 | Total for balance sheet/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.10 | Total for balance sheet/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.11 | Total for balance sheet/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.12 | Total for balance sheet/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.13 | Total for balance sheet/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 5.14 | Total for balance sheet/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x242 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.1 | Transactions in derivatives/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.2 | Transactions in derivatives/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.3 | Transactions in derivatives/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.4 | Transactions in derivatives/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.5 | Transactions in derivatives/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.6 | Transactions in derivatives/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.7 | Transactions in derivatives/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.8 | Transactions in derivatives/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.9 | Transactions in derivatives/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.10 | Transactions in derivatives/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.11 | Transactions in derivatives/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.12 | Transactions in derivatives/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.13 | Transactions in derivatives/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 6.14 | Transactions in derivatives/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x18 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.1 | Off balance sheet exposures/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.2 | Off balance sheet exposures/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.3 | Off balance sheet exposures/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.4 | Off balance sheet exposures/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.5 | Off balance sheet exposures/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.6 | Off balance sheet exposures/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.7 | Off balance sheet exposures/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.8 | Off balance sheet exposures/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.9 | Off balance sheet exposures/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.10 | Off balance sheet exposures/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.11 | Off balance sheet exposures/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.12 | Off balance sheet exposures/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.13 | Off balance sheet exposures/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r9.14 | Off balance sheet exposures/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | N/A | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.1 | Credit lines/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.2 | Credit lines/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.3 | Credit lines/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.4 | Credit lines/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.5 | Credit lines/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.6 | Credit lines/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.7 | Credit lines/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.8 | Credit lines/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.9 | Credit lines/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.10 | Credit lines/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.11 | Credit lines/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.12 | Credit lines/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.13 | Credit lines/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 7.14 | Credit lines/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x244 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.1 | Other/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.2 | Other/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.3 | Other/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.4 | Other/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.5 | Other/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.6 | Other/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.7 | Other/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.8 | Other/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.9 | Other/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.10 | Other/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.11 | Other/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.12 | Other/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.13 | Other/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 8.14 | Other/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x245 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.1 | Total off balance sheet/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.2 | Total off balance sheet/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.3 | Total off balance sheet/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.4 | Total off balance sheet/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.5 | Total off balance sheet/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.6 | Total off balance sheet/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.7 | Total off balance sheet/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.8 | Total off balance sheet/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.9 | Total off balance sheet/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.10 | Total off balance sheet/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.11 | Total off balance sheet/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.12 | Total off balance sheet/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.13 | Total off balance sheet/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 9.14 | Total off balance sheet/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.1 | Of which:/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.2 | Of which:/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.3 | Of which:/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.4 | Of which:/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.5 | Of which:/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.6 | Of which:/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.7 | Of which:/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.8 | Of which:/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.9 | Of which:/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.10 | Of which:/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.11 | Of which:/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.12 | Of which:/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.13 | Of which:/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r13.14 | Of which:/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 10.1 | 0% conversion coefficient/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.2 | 0% conversion coefficient/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.3 | 0% conversion coefficient/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.4 | 0% conversion coefficient/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.5 | 0% conversion coefficient/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.6 | 0% conversion coefficient/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.7 | 0% conversion coefficient/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.8 | 0% conversion coefficient/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.9 | 0% conversion coefficient/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.10 | 0% conversion coefficient/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.11 | 0% conversion coefficient/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.12 | 0% conversion coefficient/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.13 | 0% conversion coefficient/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 10.14 | 0% conversion coefficient/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x5 | N/A | boi_RT:x1 | N/A | N/A |
| 11.1 | 20% conversion coefficient/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.2 | 20% conversion coefficient/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.3 | 20% conversion coefficient/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.4 | 20% conversion coefficient/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.5 | 20% conversion coefficient/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.6 | 20% conversion coefficient/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.7 | 20% conversion coefficient/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.8 | 20% conversion coefficient/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.9 | 20% conversion coefficient/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.10 | 20% conversion coefficient/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.11 | 20% conversion coefficient/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.12 | 20% conversion coefficient/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.13 | 20% conversion coefficient/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 11.14 | 20% conversion coefficient/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x7 | N/A | boi_RT:x1 | N/A | N/A |
| 12.1 | 50% conversion coefficient/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.2 | 50% conversion coefficient/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.3 | 50% conversion coefficient/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.4 | 50% conversion coefficient/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.5 | 50% conversion coefficient/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.6 | 50% conversion coefficient/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.7 | 50% conversion coefficient/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.8 | 50% conversion coefficient/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.9 | 50% conversion coefficient/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.10 | 50% conversion coefficient/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.11 | 50% conversion coefficient/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.12 | 50% conversion coefficient/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.13 | 50% conversion coefficient/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 12.14 | 50% conversion coefficient/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x9 | N/A | boi_RT:x1 | N/A | N/A |
| 13.1 | 100% conversion coefficient/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.2 | 100% conversion coefficient/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.3 | 100% conversion coefficient/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.4 | 100% conversion coefficient/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.5 | 100% conversion coefficient/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.6 | 100% conversion coefficient/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.7 | 100% conversion coefficient/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.8 | 100% conversion coefficient/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.9 | 100% conversion coefficient/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.10 | 100% conversion coefficient/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.11 | 100% conversion coefficient/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.12 | 100% conversion coefficient/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.13 | 100% conversion coefficient/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| 13.14 | 100% conversion coefficient/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x243 | boi_PI:x11 | N/A | boi_RT:x1 | N/A | N/A |
| r18.1 | C. Breakdown of exposures by risk weights/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.2 | C. Breakdown of exposures by risk weights/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.3 | C. Breakdown of exposures by risk weights/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.4 | C. Breakdown of exposures by risk weights/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.5 | C. Breakdown of exposures by risk weights/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.6 | C. Breakdown of exposures by risk weights/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.7 | C. Breakdown of exposures by risk weights/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.8 | C. Breakdown of exposures by risk weights/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.9 | C. Breakdown of exposures by risk weights/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.10 | C. Breakdown of exposures by risk weights/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.11 | C. Breakdown of exposures by risk weights/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.12 | C. Breakdown of exposures by risk weights/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.13 | C. Breakdown of exposures by risk weights/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| r18.14 | C. Breakdown of exposures by risk weights/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | N/A | boi_RT:x1 | N/A | N/A |
| 14.1 | 0%/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.2 | 0%/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.3 | 0%/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.4 | 0%/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.5 | 0%/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.6 | 0%/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.7 | 0%/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.8 | 0%/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.9 | 0%/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.10 | 0%/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.11 | 0%/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.12 | 0%/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.13 | 0%/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 14.14 | 0%/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x5 | boi_RT:x1 | N/A | N/A |
| 15.1 | 20%/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.2 | 20%/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.3 | 20%/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.4 | 20%/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.5 | 20%/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.6 | 20%/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.7 | 20%/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.8 | 20%/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.9 | 20%/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.10 | 20%/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.11 | 20%/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.12 | 20%/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.13 | 20%/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 15.14 | 20%/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x7 | boi_RT:x1 | N/A | N/A |
| 16.1 | 50%/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.2 | 50%/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.3 | 50%/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.4 | 50%/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.5 | 50%/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.6 | 50%/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.7 | 50%/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.8 | 50%/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.9 | 50%/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.10 | 50%/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.11 | 50%/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.12 | 50%/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.13 | 50%/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 16.14 | 50%/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x9 | boi_RT:x1 | N/A | N/A |
| 17.1 | 100%/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.2 | 100%/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.3 | 100%/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.4 | 100%/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.5 | 100%/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.6 | 100%/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.7 | 100%/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.8 | 100%/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.9 | 100%/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.10 | 100%/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.11 | 100%/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.12 | 100%/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.13 | 100%/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 17.14 | 100%/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.1 | Of which:/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.2 | Of which:/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.3 | Of which:/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.4 | Of which:/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.5 | Of which:/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.6 | Of which:/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.7 | Of which:/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.8 | Of which:/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.9 | Of which:/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.10 | Of which:/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.11 | Of which:/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.12 | Of which:/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.13 | Of which:/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| r23.14 | Of which:/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | N/A |
| 18.1 | delinquent/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.2 | delinquent/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.3 | delinquent/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.4 | delinquent/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.5 | delinquent/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.6 | delinquent/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.7 | delinquent/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.8 | delinquent/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.9 | delinquent/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.10 | delinquent/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.11 | delinquent/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.12 | delinquent/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.13 | delinquent/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 18.14 | delinquent/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | N/A | boi_TI:x2 |
| 19.1 | Without outside credit valuation/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.2 | Without outside credit valuation/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.3 | Without outside credit valuation/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.4 | Without outside credit valuation/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.5 | Without outside credit valuation/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.6 | Without outside credit valuation/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.7 | Without outside credit valuation/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.8 | Without outside credit valuation/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.9 | Without outside credit valuation/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.10 | Without outside credit valuation/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.11 | Without outside credit valuation/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.12 | Without outside credit valuation/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.13 | Without outside credit valuation/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 19.14 | Without outside credit valuation/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x11 | boi_RT:x1 | boi_ST:x17 | N/A |
| 20.1 | 150%/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.2 | 150%/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.3 | 150%/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.4 | 150%/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.5 | 150%/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.6 | 150%/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.7 | 150%/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.8 | 150%/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.9 | 150%/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.10 | 150%/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.11 | 150%/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.12 | 150%/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.13 | 150%/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 20.14 | 150%/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | N/A |
| 21.1 | Thereof: delinquent/Exposure before credit loss provisions (before conversion into credit | boi_met:mi17 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.2 | Thereof: delinquent/Exposure after credit loss provisions (before conversion into credit) | boi_met:mi18 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.3 | Thereof: delinquent/Guarantees | boi_met:mi19 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.4 | Thereof: delinquent/Credit derivatives | boi_met:mi20 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.5 | Thereof: delinquent/Collateral - simple approach | boi_met:mi21 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.6 | Thereof: delinquent/Sums subtracted (-) | boi_met:mi22 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.7 | Thereof: delinquent/Sums added (+) | boi_met:mi23 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.8 | Thereof: delinquent/Net exposure after effects of CRM substitution and before conversion coefficients | boi_met:mi24 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.9 | Thereof: delinquent/Adjustment for exposure volatility (He) | boi_met:mi25 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.10 | Thereof: delinquent/Adjusted value of financial security(-) | boi_met:mi26 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.11 | Thereof: delinquent/Volatility and maturity adjustment(-) | boi_met:mi27 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.12 | Thereof: delinquent/Size of exposure after credit mitigation (before conversion into credit) | boi_met:mi28 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.13 | Thereof: delinquent/Size of exposure after conversion into credit | boi_met:mi29 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |
| 21.14 | Thereof: delinquent/Risk-Weighted Assets (RWA) | boi_met:mi30 | xbrli:monetaryItemType | instant | boi_BC:x16 | boi_CS:x2 | boi_EC:x1 | boi_MC:x241 | N/A | boi_PI:x12 | boi_RT:x1 | N/A | boi_TI:x2 |