| r0.1 | label_boi_a2/Delinquent 30-89 days | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x1 |
| r0.2 | label_boi_a2/90 days - 6 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x46 |
| r0.3 | label_boi_a2/>6 mo. - 15 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x47 |
| r0.4 | label_boi_a2/> 15 mo. - 33 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x48 |
| r0.5 | label_boi_a2/> 33 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x49 |
| r0.6 | label_boi_a2/Total | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x2 |
| r0.7 | label_boi_a2/Balances on acct. of recycled delinquent housing loans | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | N/A | boi_ST:x3 | boi_ST:x25 | N/A |
| r0.8 | label_boi_a2/Delinquent 30-89 days | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x1 |
| r0.9 | label_boi_a2/90 days - 6 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x46 |
| r0.10 | label_boi_a2/>6 mo. - 15 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x47 |
| r0.11 | label_boi_a2/> 15 mo. - 33 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x48 |
| r0.12 | label_boi_a2/> 33 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x49 |
| r0.13 | label_boi_a2/Total | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | N/A | N/A | N/A | boi_TI:x2 |
| r0.14 | label_boi_a2/Balances on acct. of recycled delinquent housing loans | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | N/A | boi_ST:x3 | boi_ST:x25 | N/A |
| r1.1 | Loans provisioned on basis of depth of delinquency/Delinquent 30-89 days | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| r1.2 | Loans provisioned on basis of depth of delinquency/90 days - 6 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| r1.3 | Loans provisioned on basis of depth of delinquency/>6 mo. - 15 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| r1.4 | Loans provisioned on basis of depth of delinquency/> 15 mo. - 33 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| r1.5 | Loans provisioned on basis of depth of delinquency/> 33 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| r1.6 | Loans provisioned on basis of depth of delinquency/Total | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| r1.7 | Loans provisioned on basis of depth of delinquency/Balances on acct. of recycled delinquent housing loans | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| r1.8 | Loans provisioned on basis of depth of delinquency/Delinquent 30-89 days | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| r1.9 | Loans provisioned on basis of depth of delinquency/90 days - 6 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| r1.10 | Loans provisioned on basis of depth of delinquency/>6 mo. - 15 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| r1.11 | Loans provisioned on basis of depth of delinquency/> 15 mo. - 33 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| r1.12 | Loans provisioned on basis of depth of delinquency/> 33 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| r1.13 | Loans provisioned on basis of depth of delinquency/Total | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| r1.14 | Loans provisioned on basis of depth of delinquency/Balances on acct. of recycled delinquent housing loans | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 1.1 | Sum of arrears/Delinquent 30-89 days | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 1.2 | Sum of arrears/90 days - 6 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 1.3 | Sum of arrears/>6 mo. - 15 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 1.4 | Sum of arrears/> 15 mo. - 33 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 1.5 | Sum of arrears/> 33 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 1.6 | Sum of arrears/Total | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 1.7 | Sum of arrears/Balances on acct. of recycled delinquent housing loans | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 1.8 | Sum of arrears/Delinquent 30-89 days | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 1.9 | Sum of arrears/90 days - 6 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 1.10 | Sum of arrears/>6 mo. - 15 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 1.11 | Sum of arrears/> 15 mo. - 33 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 1.12 | Sum of arrears/> 33 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 1.13 | Sum of arrears/Total | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 1.14 | Sum of arrears/Balances on acct. of recycled delinquent housing loans | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 2.1 | Thereof: balance of interest provision/Delinquent 30-89 days | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 2.2 | Thereof: balance of interest provision/90 days - 6 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 2.3 | Thereof: balance of interest provision/>6 mo. - 15 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 2.4 | Thereof: balance of interest provision/> 15 mo. - 33 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 2.5 | Thereof: balance of interest provision/> 33 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 2.6 | Thereof: balance of interest provision/Total | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 2.7 | Thereof: balance of interest provision/Balances on acct. of recycled delinquent housing loans | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 2.8 | Thereof: balance of interest provision/Delinquent 30-89 days | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 2.9 | Thereof: balance of interest provision/90 days - 6 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 2.10 | Thereof: balance of interest provision/>6 mo. - 15 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 2.11 | Thereof: balance of interest provision/> 15 mo. - 33 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 2.12 | Thereof: balance of interest provision/> 33 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 2.13 | Thereof: balance of interest provision/Total | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 2.14 | Thereof: balance of interest provision/Balances on acct. of recycled delinquent housing loans | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 3.1 | Recorded balance of debt/Delinquent 30-89 days | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 3.2 | Recorded balance of debt/90 days - 6 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 3.3 | Recorded balance of debt/>6 mo. - 15 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 3.4 | Recorded balance of debt/> 15 mo. - 33 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 3.5 | Recorded balance of debt/> 33 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 3.6 | Recorded balance of debt/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 3.7 | Recorded balance of debt/Balances on acct. of recycled delinquent housing loans | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 3.8 | Recorded balance of debt/Delinquent 30-89 days | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 3.9 | Recorded balance of debt/90 days - 6 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 3.10 | Recorded balance of debt/>6 mo. - 15 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 3.11 | Recorded balance of debt/> 15 mo. - 33 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 3.12 | Recorded balance of debt/> 33 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 3.13 | Recorded balance of debt/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 3.14 | Recorded balance of debt/Balances on acct. of recycled delinquent housing loans | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 4.1 | Balance of credit loss provision/Delinquent 30-89 days | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 4.2 | Balance of credit loss provision/90 days - 6 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 4.3 | Balance of credit loss provision/>6 mo. - 15 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 4.4 | Balance of credit loss provision/> 15 mo. - 33 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 4.5 | Balance of credit loss provision/> 33 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 4.6 | Balance of credit loss provision/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 4.7 | Balance of credit loss provision/Balances on acct. of recycled delinquent housing loans | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 4.8 | Balance of credit loss provision/Delinquent 30-89 days | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 4.9 | Balance of credit loss provision/90 days - 6 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 4.10 | Balance of credit loss provision/>6 mo. - 15 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 4.11 | Balance of credit loss provision/> 15 mo. - 33 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 4.12 | Balance of credit loss provision/> 33 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 4.13 | Balance of credit loss provision/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 4.14 | Balance of credit loss provision/Balances on acct. of recycled delinquent housing loans | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 5.1 | Net balance of debt/Delinquent 30-89 days | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 5.2 | Net balance of debt/90 days - 6 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 5.3 | Net balance of debt/>6 mo. - 15 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 5.4 | Net balance of debt/> 15 mo. - 33 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 5.5 | Net balance of debt/> 33 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 5.6 | Net balance of debt/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 5.7 | Net balance of debt/Balances on acct. of recycled delinquent housing loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 5.8 | Net balance of debt/Delinquent 30-89 days | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 5.9 | Net balance of debt/90 days - 6 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 5.10 | Net balance of debt/>6 mo. - 15 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 5.11 | Net balance of debt/> 15 mo. - 33 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 5.12 | Net balance of debt/> 33 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 5.13 | Net balance of debt/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 5.14 | Net balance of debt/Balances on acct. of recycled delinquent housing loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 6.1 | No. of loans/Delinquent 30-89 days | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 6.2 | No. of loans/90 days - 6 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 6.3 | No. of loans/>6 mo. - 15 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 6.4 | No. of loans/> 15 mo. - 33 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 6.5 | No. of loans/> 33 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 6.6 | No. of loans/Total | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 6.7 | No. of loans/Balances on acct. of recycled delinquent housing loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| 6.8 | No. of loans/Delinquent 30-89 days | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x1 |
| 6.9 | No. of loans/90 days - 6 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x46 |
| 6.10 | No. of loans/>6 mo. - 15 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x47 |
| 6.11 | No. of loans/> 15 mo. - 33 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x48 |
| 6.12 | No. of loans/> 33 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x49 |
| 6.13 | No. of loans/Total | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | N/A | N/A | boi_TI:x2 |
| 6.14 | No. of loans/Balances on acct. of recycled delinquent housing loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x96 | boi_ST:x3 | boi_ST:x25 | N/A |
| r8.1 | Loans not provisioned on basis of depth of delinquency/Delinquent 30-89 days | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| r8.2 | Loans not provisioned on basis of depth of delinquency/90 days - 6 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| r8.3 | Loans not provisioned on basis of depth of delinquency/>6 mo. - 15 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| r8.4 | Loans not provisioned on basis of depth of delinquency/> 15 mo. - 33 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| r8.5 | Loans not provisioned on basis of depth of delinquency/> 33 mo. | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| r8.6 | Loans not provisioned on basis of depth of delinquency/Total | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| r8.7 | Loans not provisioned on basis of depth of delinquency/Balances on acct. of recycled delinquent housing loans | | | | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| r8.8 | Loans not provisioned on basis of depth of delinquency/Delinquent 30-89 days | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| r8.9 | Loans not provisioned on basis of depth of delinquency/90 days - 6 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| r8.10 | Loans not provisioned on basis of depth of delinquency/>6 mo. - 15 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| r8.11 | Loans not provisioned on basis of depth of delinquency/> 15 mo. - 33 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| r8.12 | Loans not provisioned on basis of depth of delinquency/> 33 mo. | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| r8.13 | Loans not provisioned on basis of depth of delinquency/Total | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| r8.14 | Loans not provisioned on basis of depth of delinquency/Balances on acct. of recycled delinquent housing loans | | | | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 7.1 | Sum of arrears/Delinquent 30-89 days | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 7.2 | Sum of arrears/90 days - 6 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 7.3 | Sum of arrears/>6 mo. - 15 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 7.4 | Sum of arrears/> 15 mo. - 33 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 7.5 | Sum of arrears/> 33 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 7.6 | Sum of arrears/Total | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 7.7 | Sum of arrears/Balances on acct. of recycled delinquent housing loans | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 7.8 | Sum of arrears/Delinquent 30-89 days | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 7.9 | Sum of arrears/90 days - 6 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 7.10 | Sum of arrears/>6 mo. - 15 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 7.11 | Sum of arrears/> 15 mo. - 33 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 7.12 | Sum of arrears/> 33 mo. | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 7.13 | Sum of arrears/Total | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 7.14 | Sum of arrears/Balances on acct. of recycled delinquent housing loans | boi_met:mi546 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 8.1 | Thereof: balance of interest provision/Delinquent 30-89 days | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 8.2 | Thereof: balance of interest provision/90 days - 6 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 8.3 | Thereof: balance of interest provision/>6 mo. - 15 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 8.4 | Thereof: balance of interest provision/> 15 mo. - 33 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 8.5 | Thereof: balance of interest provision/> 33 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 8.6 | Thereof: balance of interest provision/Total | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 8.7 | Thereof: balance of interest provision/Balances on acct. of recycled delinquent housing loans | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 8.8 | Thereof: balance of interest provision/Delinquent 30-89 days | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 8.9 | Thereof: balance of interest provision/90 days - 6 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 8.10 | Thereof: balance of interest provision/>6 mo. - 15 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 8.11 | Thereof: balance of interest provision/> 15 mo. - 33 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 8.12 | Thereof: balance of interest provision/> 33 mo. | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 8.13 | Thereof: balance of interest provision/Total | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 8.14 | Thereof: balance of interest provision/Balances on acct. of recycled delinquent housing loans | boi_met:mi547 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 9.1 | Recorded balance of debt/Delinquent 30-89 days | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 9.2 | Recorded balance of debt/90 days - 6 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 9.3 | Recorded balance of debt/>6 mo. - 15 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 9.4 | Recorded balance of debt/> 15 mo. - 33 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 9.5 | Recorded balance of debt/> 33 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 9.6 | Recorded balance of debt/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 9.7 | Recorded balance of debt/Balances on acct. of recycled delinquent housing loans | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 9.8 | Recorded balance of debt/Delinquent 30-89 days | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 9.9 | Recorded balance of debt/90 days - 6 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 9.10 | Recorded balance of debt/>6 mo. - 15 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 9.11 | Recorded balance of debt/> 15 mo. - 33 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 9.12 | Recorded balance of debt/> 33 mo. | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 9.13 | Recorded balance of debt/Total | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 9.14 | Recorded balance of debt/Balances on acct. of recycled delinquent housing loans | boi_met:mi2 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 10.1 | Balance of credit loss provision/Delinquent 30-89 days | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 10.2 | Balance of credit loss provision/90 days - 6 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 10.3 | Balance of credit loss provision/>6 mo. - 15 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 10.4 | Balance of credit loss provision/> 15 mo. - 33 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 10.5 | Balance of credit loss provision/> 33 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 10.6 | Balance of credit loss provision/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 10.7 | Balance of credit loss provision/Balances on acct. of recycled delinquent housing loans | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 10.8 | Balance of credit loss provision/Delinquent 30-89 days | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 10.9 | Balance of credit loss provision/90 days - 6 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 10.10 | Balance of credit loss provision/>6 mo. - 15 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 10.11 | Balance of credit loss provision/> 15 mo. - 33 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 10.12 | Balance of credit loss provision/> 33 mo. | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 10.13 | Balance of credit loss provision/Total | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 10.14 | Balance of credit loss provision/Balances on acct. of recycled delinquent housing loans | boi_met:mi3 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 11.1 | Net balance of debt/Delinquent 30-89 days | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 11.2 | Net balance of debt/90 days - 6 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 11.3 | Net balance of debt/>6 mo. - 15 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 11.4 | Net balance of debt/> 15 mo. - 33 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 11.5 | Net balance of debt/> 33 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 11.6 | Net balance of debt/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 11.7 | Net balance of debt/Balances on acct. of recycled delinquent housing loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 11.8 | Net balance of debt/Delinquent 30-89 days | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 11.9 | Net balance of debt/90 days - 6 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 11.10 | Net balance of debt/>6 mo. - 15 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 11.11 | Net balance of debt/> 15 mo. - 33 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 11.12 | Net balance of debt/> 33 mo. | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 11.13 | Net balance of debt/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 11.14 | Net balance of debt/Balances on acct. of recycled delinquent housing loans | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 12.1 | No. of loans/Delinquent 30-89 days | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 12.2 | No. of loans/90 days - 6 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 12.3 | No. of loans/>6 mo. - 15 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 12.4 | No. of loans/> 15 mo. - 33 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 12.5 | No. of loans/> 33 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 12.6 | No. of loans/Total | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 12.7 | No. of loans/Balances on acct. of recycled delinquent housing loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x36 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |
| 12.8 | No. of loans/Delinquent 30-89 days | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x1 |
| 12.9 | No. of loans/90 days - 6 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x46 |
| 12.10 | No. of loans/>6 mo. - 15 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x47 |
| 12.11 | No. of loans/> 15 mo. - 33 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x48 |
| 12.12 | No. of loans/> 33 mo. | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x49 |
| 12.13 | No. of loans/Total | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | N/A | N/A | boi_TI:x2 |
| 12.14 | No. of loans/Balances on acct. of recycled delinquent housing loans | boi_met:id103 | xbrli:integerItemType | instant | boi_BC:x1 | boi_CL:x37 | boi_CS:x1 | boi_MC:x8 | boi_ST:x151 | boi_ST:x3 | boi_ST:x25 | N/A |