| r0.1 | label_boi_a2/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | | | | N/A | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x27 |
| r0.2 | label_boi_a2/Consolidated (Incl. credit companies reporting as company only) For quarter | | | | N/A | N/A | boi_CS:x2 | N/A | N/A | boi_RP:x13 |
| r1.1 | Income/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x27 |
| r1.2 | Income/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | N/A | N/A | boi_RP:x13 |
| 1.1 | Income from credit card transatcions/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | boi_MU:x1 | boi_RP:x27 |
| 1.2 | Income from credit card transatcions/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x281 | N/A | boi_RP:x13 |
| 2.1 | Interest income, net/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | boi_MU:x1 | boi_RP:x27 |
| 2.2 | Interest income, net/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x125 | N/A | boi_RP:x13 |
| 3.1 | Other income/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | boi_MU:x1 | boi_RP:x27 |
| 3.2 | Other income/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x456 | N/A | boi_RP:x13 |
| 4.1 | Total income/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | boi_MU:x1 | boi_RP:x27 |
| 4.2 | Total income/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x455 | N/A | boi_RP:x13 |
| r6.1 | Expense/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | boi_MU:x1 | boi_RP:x27 |
| r6.2 | Expense/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | N/A | N/A | boi_CS:x2 | N/A | N/A | boi_RP:x13 |
| 5.1 | Credit loss expenses/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x126 | boi_MU:x1 | boi_RP:x27 |
| 5.2 | Credit loss expenses/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x126 | N/A | boi_RP:x13 |
| 6.1 | Operational/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | boi_MU:x1 | boi_RP:x27 |
| 6.2 | Operational/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x458 | N/A | boi_RP:x13 |
| 7.1 | Sales and marketing/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x459 | boi_MU:x1 | boi_RP:x27 |
| 7.2 | Sales and marketing/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x459 | N/A | boi_RP:x13 |
| 8.1 | Administrative and general/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x460 | boi_MU:x1 | boi_RP:x27 |
| 8.2 | Administrative and general/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x460 | N/A | boi_RP:x13 |
| 9.1 | Payments to banks/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | boi_MU:x1 | boi_RP:x27 |
| 9.2 | Payments to banks/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x10 | N/A | boi_CS:x2 | boi_MC:x461 | N/A | boi_RP:x13 |
| 10.1 | Total expenses/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x457 | boi_MU:x1 | boi_RP:x27 |
| 10.2 | Total expenses/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x457 | N/A | boi_RP:x13 |
| 11.1 | Pre-tax profit/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x123 | boi_MU:x1 | boi_RP:x27 |
| 11.2 | Pre-tax profit/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x123 | N/A | boi_RP:x13 |
| 12.1 | Provision for taxes on profit/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x190 | boi_MU:x1 | boi_RP:x27 |
| 12.2 | Provision for taxes on profit/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x12 | N/A | boi_CS:x2 | boi_MC:x190 | N/A | boi_RP:x13 |
| 13.1 | Post-tax profit/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x122 | boi_MU:x1 | boi_RP:x27 |
| 13.2 | Post-tax profit/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x122 | N/A | boi_RP:x13 |
| 14.1 | Company's share in included companies' profit after tax effect/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x191 | boi_MU:x1 | boi_RP:x27 |
| 14.2 | Company's share in included companies' profit after tax effect/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x191 | N/A | boi_RP:x13 |
| r17.1 | Net profit/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x27 |
| r17.2 | Net profit/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x13 |
| 15.1 | Net profit before attribution to holders of noncontrolling rights/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x27 |
| 15.2 | Net profit before attribution to holders of noncontrolling rights/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | N/A | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x13 |
| 16.1 | Net profit attributed to holders of noncontrolling rights/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x27 |
| 16.2 | Net profit attributed to holders of noncontrolling rights/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x2 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x13 |
| 17.1 | Net profit attributed to shareholders in credit card company/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x27 |
| 17.2 | Net profit attributed to shareholders in credit card company/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md13 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x13 |
| r21.1 | Earnings per share/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | | | | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x27 |
| r21.2 | Earnings per share/Consolidated (Incl. credit companies reporting as company only) For quarter | | | | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x13 |
| 18.1 | Basic profit: Attributed to shareholders in credit card company/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md81 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x27 |
| 18.2 | Basic profit: Attributed to shareholders in credit card company/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md81 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x13 |
| 19.1 | Diluted profit: Attributed to shareholders in credit card company/Consolidated (Incl. credit companies reporting as company only) Cumulative from beginning of year | boi_met:md82 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | boi_MU:x1 | boi_RP:x27 |
| 19.2 | Diluted profit: Attributed to shareholders in credit card company/Consolidated (Incl. credit companies reporting as company only) For quarter | boi_met:md82 | xbrli:monetaryItemType | instant | boi_BC:x11 | boi_CN:x1 | boi_CS:x2 | boi_MC:x121 | N/A | boi_RP:x13 |