| r0.1 | label_boi_a2/Total balance sheet exposure | boi_met:mi540 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | N/A | boi_MC:x1 | boi_RP:x24 |
| r0.2 | label_boi_a2/Off balance sheet exposure | boi_met:mi76 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | N/A | boi_MC:x702 | boi_RP:x24 |
| r0.3 | label_boi_a2/Total | boi_met:mi1200 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | N/A | boi_MC:x928 | boi_RP:x24 |
| 22.1 | Other countries/Total balance sheet exposure | boi_met:mi540 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x22 | boi_GA:x2 | boi_MC:x1 | boi_RP:x24 |
| 22.2 | Other countries/Off balance sheet exposure | boi_met:mi76 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x22 | boi_GA:x2 | boi_MC:x702 | boi_RP:x24 |
| 22.3 | Other countries/Total | boi_met:mi1200 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x22 | boi_GA:x2 | boi_MC:x928 | boi_RP:x24 |
| 23.1 | Total exposure to foreign countries/Total balance sheet exposure | boi_met:mi540 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x1 | boi_RP:x24 |
| 23.2 | Total exposure to foreign countries/Off balance sheet exposure | boi_met:mi76 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x702 | boi_RP:x24 |
| 23.3 | Total exposure to foreign countries/Total | boi_met:mi1200 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | boi_GA:x2 | boi_MC:x928 | boi_RP:x24 |
| 24.1 | Of which: Total exposre to PIGS countries/Total balance sheet exposure | boi_met:mi540 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x22 | boi_GA:x1258 | boi_MC:x1 | boi_RP:x24 |
| 24.2 | Of which: Total exposre to PIGS countries/Off balance sheet exposure | boi_met:mi76 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x22 | boi_GA:x1258 | boi_MC:x702 | boi_RP:x24 |
| 24.3 | Of which: Total exposre to PIGS countries/Total | boi_met:mi1200 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x22 | boi_GA:x1258 | boi_MC:x928 | boi_RP:x24 |
| 25.1 | Of which: Total exposre to LDC countries/Total balance sheet exposure | boi_met:mi540 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | boi_GA:x24 | boi_MC:x1 | boi_RP:x24 |
| 25.2 | Of which: Total exposre to LDC countries/Off balance sheet exposure | boi_met:mi76 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | boi_GA:x24 | boi_MC:x702 | boi_RP:x24 |
| 25.3 | Of which: Total exposre to LDC countries/Total | boi_met:mi1200 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CS:x2 | boi_FN:x1 | N/A | N/A | boi_GA:x24 | boi_MC:x928 | boi_RP:x24 |
| 26.1 | Of which: Total exposre to foreign countries with liquidity problems/Total balance sheet exposure | boi_met:mi540 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_FN:x1 | boi_GA:x39 | N/A | boi_GA:x2 | boi_MC:x1 | boi_RP:x24 |
| 26.2 | Of which: Total exposre to foreign countries with liquidity problems/Off balance sheet exposure | boi_met:mi76 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CS:x2 | boi_FN:x1 | boi_GA:x39 | N/A | boi_GA:x2 | boi_MC:x702 | boi_RP:x24 |
| 26.3 | Of which: Total exposre to foreign countries with liquidity problems/Total | boi_met:mi1200 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CS:x2 | boi_FN:x1 | boi_GA:x39 | N/A | boi_GA:x2 | boi_MC:x928 | boi_RP:x24 |
| 27.1 | Of which: Total exposre such that each country is exposed in % of total assets or 0.51-2 % of total capital/Total balance sheet exposure | boi_met:mi540 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x27 | boi_GA:x2 | boi_MC:x1 | boi_RP:x24 |
| 27.2 | Of which: Total exposre such that each country is exposed in % of total assets or 0.51-2 % of total capital/Off balance sheet exposure | boi_met:mi76 | xbrli:monetaryItemType | instant | boi_BC:x8 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x27 | boi_GA:x2 | boi_MC:x702 | boi_RP:x24 |
| 27.3 | Of which: Total exposre such that each country is exposed in % of total assets or 0.51-2 % of total capital/Total | boi_met:mi1200 | xbrli:monetaryItemType | instant | boi_BC:x28 | boi_CS:x2 | boi_FN:x1 | N/A | boi_GA:x27 | boi_GA:x2 | boi_MC:x928 | boi_RP:x24 |