| **Loans and Allowance - Changes in Allowance for Loan Losses by Loan Segment (Detail) (USD $)In Thousands, unless otherwise specified** | 3 Months Ended                                                                                                                                                              | 12 Months Ended                                  |
|-----------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------|
||
| **Allowance for loan losses:**                                                                                                          |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |                                                                                                                                                                        |                                             |   | $ 67,870us-gaap_LoansAndLeasesReceivableAllowance |   |   |   | $ 69,366us-gaap_LoansAndLeasesReceivableAllowance | $ 67,870us-gaap_LoansAndLeasesReceivableAllowance | $ 69,366us-gaap_LoansAndLeasesReceivableAllowance | $ 70,898us-gaap_LoansAndLeasesReceivableAllowance |
| Provision for losses                                                                                                                    | 960us-gaap_ProvisionForLoanLeaseAndOtherLosses                                                                                                                              | 1,600us-gaap_ProvisionForLoanLeaseAndOtherLosses |    |    | 1,016us-gaap_ProvisionForLoanLeaseAndOtherLosses | 1,533us-gaap_ProvisionForLoanLeaseAndOtherLosses | 1,997us-gaap_ProvisionForLoanLeaseAndOtherLosses | 2,102us-gaap_ProvisionForLoanLeaseAndOtherLosses | 2,560us-gaap_ProvisionForLoanLeaseAndOtherLosses | 6,648us-gaap_ProvisionForLoanLeaseAndOtherLosses | 18,534us-gaap_ProvisionForLoanLeaseAndOtherLosses |
| Recoveries on loans                                                                                                                     |                                                                                                                                                                        |                                             |   |   |   |   |   |   | 10,916us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts | 9,990us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts | 7,206us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts |
| Loans charged off                                                                                                                       |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (17,382)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs | (18,134)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs | (27,272)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs |
| Ending balance                                                                                                                          | 63,964us-gaap_LoansAndLeasesReceivableAllowance                                                                                                                             |                                             |   |   | 67,870us-gaap_LoansAndLeasesReceivableAllowance |   |   |   | 63,964us-gaap_LoansAndLeasesReceivableAllowance | 67,870us-gaap_LoansAndLeasesReceivableAllowance | 69,366us-gaap_LoansAndLeasesReceivableAllowance |
| Commercial                                                                                                                              |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |                                                                                                                                                                        |                                             |   | 27,176us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember |   |   |   | 25,913us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 27,176us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 25,913us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 17,731us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember |
| Provision for losses                                                                                                                    |                                                                                                                                                                        |                                             |   |   |   |   |   |   | 3,459us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 2,794us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 14,749us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember |
| Recoveries on loans                                                                                                                     |                                                                                                                                                                        |                                             |   |   |   |   |   |   | 5,435us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 4,586us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 1,744us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember |
| Loans charged off                                                                                                                       |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (7,246)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | (6,117)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | (8,311)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember |
| Ending balance                                                                                                                          | 28,824us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember                |                                             |   |   | 27,176us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember |   |   |   | 28,824us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 27,176us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember | 25,913us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialLoanMember |
| Commercial Real Estate                                                                                                                  |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |                                                                                                                                                                        |                                             |   | 23,102us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember |   |   |   | 26,703us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | 23,102us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | 26,703us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | 37,919us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember |
| Provision for losses                                                                                                                    |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (464)us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | 340us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | (2,546)us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember |
| Recoveries on loans                                                                                                                     |                                                                                                                                                                        |                                             |   |   |   |   |   |   | 3,297us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | 3,552us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | 3,652us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember |
| Loans charged off                                                                                                                       |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (6,608)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | (7,493)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | (12,322)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember |
| Ending balance                                                                                                                          | 19,327us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember          |                                             |   |   | 23,102us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember |   |   |   | 19,327us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | 23,102us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember | 26,703us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_CommercialRealEstateMember |
| Consumer                                                                                                                                |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |                                                                                                                                                                        |                                             |   | 2,515us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember |   |   |   | 2,593us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | 2,515us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | 2,593us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | 2,902us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember |
| Provision for losses                                                                                                                    |                                                                                                                                                                        |                                             |   |   |   |   |   |   | 423us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | (11)us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | 126us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember |
| Recoveries on loans                                                                                                                     |                                                                                                                                                                        |                                             |   |   |   |   |   |   | 377us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | 556us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | 695us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember |
| Loans charged off                                                                                                                       |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (657)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | (623)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | (1,130)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember |
| Ending balance                                                                                                                          | 2,658us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember                   |                                             |   |   | 2,515us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember |   |   |   | 2,658us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | 2,515us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember | 2,593us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ConsumerLoanMember |
| Residential                                                                                                                             |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |                                                                                                                                                                        |                                             |   | 15,077us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember |   |   |   | 14,157us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 15,077us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 14,157us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 12,343us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember |
| Provision for losses                                                                                                                    |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (839)us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 3,514us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 6,176us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember |
| Recoveries on loans                                                                                                                     |                                                                                                                                                                        |                                             |   |   |   |   |   |   | 1,783us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 1,292us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 1,113us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember |
| Loans charged off                                                                                                                       |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (2,869)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | (3,886)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | (5,475)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember |
| Ending balance                                                                                                                          | 13,152us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember         |                                             |   |   | 15,077us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember |   |   |   | 13,152us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 15,077us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember | 14,157us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_ResidentialRealEstateMember |
| Finance Leases                                                                                                                          |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |                                                                                                                                                                        |                                             |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |                                                                                                                                                                        |                                             |   |    |   |   |   |    |    |    | 3us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember |
| Provision for losses                                                                                                                    |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (19)us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember | 11us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember | 29us-gaap_ProvisionForLoanLeaseAndOtherLosses/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember |
| Recoveries on loans                                                                                                                     |                                                                                                                                                                        |                                             |   |   |   |   |   |   | 24us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember | 4us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember | 2us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember |
| Loans charged off                                                                                                                       |                                                                                                                                                                        |                                             |   |   |   |   |   |   | (2)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember | (15)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember | (34)us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember |
| Ending balance                                                                                                                          | $ 3us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember |                                             |   |   |    |   |   |   | $ 3us-gaap_LoansAndLeasesReceivableAllowance/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis= us-gaap_FinanceLeasesFinancingReceivableMember |    |    |

| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AllowanceForLoanAndLeaseLossesRollForward**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524
+ Details**Name:**us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524
+ Details**Name:**us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (b)(1)(ii) -URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section L -Subsection 1
+ Details**Name:**us-gaap_LoansAndLeasesReceivableAllowance**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 11 -Article 9Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.11) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524
+ Details**Name:**us-gaap_ProvisionForLoanLeaseAndOtherLosses**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerLoanMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_FinanceLeasesFinancingReceivableMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialRealEstateMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |