| r0.1 | label_boi_a2/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | N/A | N/A | boi_MU:x1 | N/A | boi_RP:x25 |
| r0.2 | label_boi_a2/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x1 | N/A | N/A | N/A | boi_MU:x1 | N/A | boi_RP:x25 |
| r1.1 | Non-interest financing income in respect of activities for trading purposes/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x2 | N/A | N/A | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| r1.2 | Non-interest financing income in respect of activities for trading purposes/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | boi_CS:x1 | N/A | N/A | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 1.1 | Other income (expense) ,net other derivatives/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 1.2 | Other income (expense) ,net other derivatives/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 2.1 | Gains (Losses) realized and unrealized fair value of debentures held for trading, net/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x130 | boi_MC:x15 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 2.2 | Gains (Losses) realized and unrealized fair value of debentures held for trading, net/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x130 | boi_MC:x15 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 3.1 | Of which: Part of gains and losses related to trading bonds still held at the balance sheet total/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x134 | boi_MC:x15 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 3.2 | Of which: Part of gains and losses related to trading bonds still held at the balance sheet total/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x134 | boi_MC:x15 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 4.1 | Gains (Losses) realized and unrealized fair value of shares held for trading, net/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x130 | boi_MC:x30 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 4.2 | Gains (Losses) realized and unrealized fair value of shares held for trading, net/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x130 | boi_MC:x30 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 5.1 | Of which: Part of gains and losses related to trading shares still held at the balance sheet total/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x134 | boi_MC:x30 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 5.2 | Of which: Part of gains and losses related to trading shares still held at the balance sheet total/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x134 | boi_MC:x30 | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 6.1 | Dividends recived from trading activities/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x2 | N/A | boi_MC:x137 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 6.2 | Dividends recived from trading activities/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x9 | boi_CS:x1 | N/A | boi_MC:x137 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 7.1 | Total trading activites/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 7.2 | Total trading activites/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| r9.1 | Non-interest financing income in respect of activities for trading purposes by risk exposure/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| r9.2 | Non-interest financing income in respect of activities for trading purposes by risk exposure/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 8.1 | Interest exposure/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_EC:x22 | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 8.2 | Interest exposure/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | boi_EC:x22 | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 9.1 | Foreign currency exposure/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_EC:x23 | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 9.2 | Foreign currency exposure/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | boi_EC:x23 | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 10.1 | Shares exposure/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_EC:x24 | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 10.2 | Shares exposure/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | boi_EC:x24 | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 11.1 | Exposure to commodities and other/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | boi_EC:x25 | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 11.2 | Exposure to commodities and other/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | boi_EC:x25 | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 12.1 | Total/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| 12.2 | Total/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x128 | N/A | boi_MU:x1 | boi_PL:x2 | boi_RP:x25 |
| r15.1 | Ineffective portion of hedge transactions/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | N/A | boi_RP:x25 |
| r15.2 | Ineffective portion of hedge transactions/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | N/A | boi_RP:x25 |
| r16.1 | Fair value hedges:/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | N/A | boi_RP:x25 |
| r16.2 | Fair value hedges:/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | N/A | boi_RP:x25 |
| 13.1 | The lack of effectiveness of hedges/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x20 | boi_RP:x25 |
| 13.2 | The lack of effectiveness of hedges/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x20 | boi_RP:x25 |
| 14.1 | Component of income (loss), which was issued in order to asses hedge effectiveness/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x21 | boi_RP:x25 |
| 14.2 | Component of income (loss), which was issued in order to asses hedge effectiveness/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x21 | boi_RP:x25 |
| 15.1 | Gains (Losses) net, for a firm commitment that no longer fit as a fair value hedge/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x22 | boi_RP:x25 |
| 15.2 | Gains (Losses) net, for a firm commitment that no longer fit as a fair value hedge/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x22 | boi_RP:x25 |
| r20.1 | Fair value hedges:/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | N/A | boi_RP:x25 |
| r20.2 | Fair value hedges:/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | N/A | boi_RP:x25 |
| 16.1 | The lack of effectiveness of hedges/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x23 | boi_RP:x25 |
| 16.2 | The lack of effectiveness of hedges/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x23 | boi_RP:x25 |
| 17.1 | Component of income (loss), which was issued in order to asses hedge effectiveness/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x24 | boi_RP:x25 |
| 17.2 | Component of income (loss), which was issued in order to asses hedge effectiveness/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x24 | boi_RP:x25 |
| 18.1 | Gains (Losses) reclassified from transactions not go through apparently/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x25 | boi_RP:x25 |
| 18.2 | Gains (Losses) reclassified from transactions not go through apparently/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x25 | boi_RP:x25 |
| 19.1 | Total/Consolidated | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x2 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x19 | boi_RP:x25 |
| 19.2 | Total/Bank Corporation | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CS:x1 | N/A | boi_MC:x127 | boi_MC:x18 | boi_MU:x1 | boi_PL:x19 | boi_RP:x25 |