| r0.1 | label_boi_a2/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | N/A | boi_RP:x25 |
| r0.2 | label_boi_a2/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | N/A | boi_RP:x25 |
| r0.3 | label_boi_a2/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 |
| r1.1 | Changes in the components of other comprehensive income (loss) before attribution to non-controlling interests/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | N/A | boi_RP:x25 |
| r1.2 | Changes in the components of other comprehensive income (loss) before attribution to non-controlling interests/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | N/A | boi_RP:x25 |
| r1.3 | Changes in the components of other comprehensive income (loss) before attribution to non-controlling interests/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 |
| r2.1 | Adjustment in respect of statement of bonds available at fair value/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | N/A | boi_RP:x25 |
| r2.2 | Adjustment in respect of statement of bonds available at fair value/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | N/A | boi_RP:x25 |
| r2.3 | Adjustment in respect of statement of bonds available at fair value/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 |
| 1.1 | Gains (losses) from fair value adjustment/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x28 | boi_RP:x25 |
| 1.2 | Gains (losses) from fair value adjustment/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x28 | boi_RP:x25 |
| 1.3 | Gains (losses) from fair value adjustment/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x28 | boi_RP:x25 |
| 2.1 | Gains (losses) on bonds available for sale reclassified to profit or loss/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x29 | boi_RP:x25 |
| 2.2 | Gains (losses) on bonds available for sale reclassified to profit or loss/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x29 | boi_RP:x25 |
| 2.3 | Gains (losses) on bonds available for sale reclassified to profit or loss/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x29 | boi_RP:x25 |
| 3.1 | Total of securities available for sale/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x1 | boi_RP:x25 |
| 3.2 | Total of securities available for sale/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x1 | boi_RP:x25 |
| 3.3 | Total of securities available for sale/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x1 | boi_RP:x25 |
| r6.1 | Traslation adjustments/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | N/A | boi_RP:x25 |
| r6.2 | Traslation adjustments/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | N/A | boi_RP:x25 |
| r6.3 | Traslation adjustments/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 |
| 4.1 | Foreign currency translation adjustment/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x31 | boi_RP:x25 |
| 4.2 | Foreign currency translation adjustment/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x31 | boi_RP:x25 |
| 4.3 | Foreign currency translation adjustment/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x31 | boi_RP:x25 |
| 5.1 | Hedging/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x32 | boi_RP:x25 |
| 5.2 | Hedging/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x32 | boi_RP:x25 |
| 5.3 | Hedging/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x32 | boi_RP:x25 |
| 6.1 | Net gains (losses) reclassified to profit or loss including realization of activity/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x33 | boi_RP:x25 |
| 6.2 | Net gains (losses) reclassified to profit or loss including realization of activity/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x33 | boi_RP:x25 |
| 6.3 | Net gains (losses) reclassified to profit or loss including realization of activity/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x33 | boi_RP:x25 |
| 7.1 | Net change during the year/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x30 | boi_RP:x25 |
| 7.2 | Net change during the year/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x30 | boi_RP:x25 |
| 7.3 | Net change during the year/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x30 | boi_RP:x25 |
| r11.1 | Hedging cash flow/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | N/A | boi_RP:x25 |
| r11.2 | Hedging cash flow/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | N/A | boi_RP:x25 |
| r11.3 | Hedging cash flow/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 |
| 8.1 | Gains (losses) from fair value adjustment/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x34 | boi_RP:x25 |
| 8.2 | Gains (losses) from fair value adjustment/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x34 | boi_RP:x25 |
| 8.3 | Gains (losses) from fair value adjustment/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x34 | boi_RP:x25 |
| 9.1 | Gains (losses) on securities available for sale reclassified to profit or loss/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x35 | boi_RP:x25 |
| 9.2 | Gains (losses) on securities available for sale reclassified to profit or loss/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x35 | boi_RP:x25 |
| 9.3 | Gains (losses) on securities available for sale reclassified to profit or loss/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x35 | boi_RP:x25 |
| 10.1 | Net change during the year/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x27 | boi_RP:x25 |
| 10.2 | Net change during the year/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x27 | boi_RP:x25 |
| 10.3 | Net change during the year/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x27 | boi_RP:x25 |
| r15.1 | Employee rights/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | N/A | boi_RP:x25 |
| r15.2 | Employee rights/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | N/A | boi_RP:x25 |
| r15.3 | Employee rights/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | N/A | boi_RP:x25 |
| 11.1 | Net gains (losses)/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x54 | boi_RP:x25 |
| 11.2 | Net gains (losses)/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x54 | boi_RP:x25 |
| 11.3 | Net gains (losses)/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x54 | boi_RP:x25 |
| 12.1 | Credit/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x55 | boi_RP:x25 |
| 12.2 | Credit/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x55 | boi_RP:x25 |
| 12.3 | Credit/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x55 | boi_RP:x25 |
| 13.1 | Gains (losses) from fair value adjustment/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x56 | boi_RP:x25 |
| 13.2 | Gains (losses) from fair value adjustment/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x56 | boi_RP:x25 |
| 13.3 | Gains (losses) from fair value adjustment/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x56 | boi_RP:x25 |
| 14.1 | Other/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x57 | boi_RP:x25 |
| 14.2 | Other/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x57 | boi_RP:x25 |
| 14.3 | Other/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x57 | boi_RP:x25 |
| 15.1 | Net change during the year/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x53 | boi_RP:x25 |
| 15.2 | Net change during the year/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x53 | boi_RP:x25 |
| 15.3 | Net change during the year/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x53 | boi_RP:x25 |
| 16.1 | Total change during the year/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |
| 16.2 | Total change during the year/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |
| 16.3 | Total change during the year/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |
| 17.1 | Change during the year attributable to non-controlling interests/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |
| 17.2 | Change during the year attributable to non-controlling interests/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |
| 17.3 | Change during the year attributable to non-controlling interests/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |
| 18.1 | Change during the year attributable to shareholders of the banking corporation/Before tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x406 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |
| 18.2 | Change during the year attributable to shareholders of the banking corporation/Tax effect | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x408 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |
| 18.3 | Change during the year attributable to shareholders of the banking corporation/After tax | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x399 | boi_MU:x1 | boi_PL:x36 | boi_RP:x25 |