| **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                                                                                                                       |           |            |   | $ 69,366 |   |   |   | $ 70,898 | $ 69,366 | $ 70,898 | $ 82,977 |
| Provision for losses                                                                                                                    | 1,016          | 1,533           | 1,997 | 2,102 | 4,505 | 4,609 | 4,545 | 4,875 | 6,648 | 18,534 | 22,630 |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 9,990 | 7,206 | 13,764 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (18,134) | (27,272) | (48,473) |
| Ending balance                                                                                                                          | 67,870         |            |   |   | 69,366 |   |   |   | 67,870 | 69,366 | 70,898 |
| Commercial                                                                                                                              |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 25,913 |   |   |   | 17,731 | 25,913 | 17,731 | 32,508 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | 2,794 | 14,749 | (13,787) |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 4,586 | 1,744 | 8,828 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (6,117) | (8,311) | (9,818) |
| Ending balance                                                                                                                          | 27,176         |            |   |   | 25,913 |   |   |   | 27,176 | 25,913 | 17,731 |
| Commercial Real Estate                                                                                                                  |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 26,703 |   |   |   | 37,919 | 26,703 | 37,919 | 36,341 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | 340 | (2,546) | 28,574 |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 3,552 | 3,652 | 2,811 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (7,493) | (12,322) | (29,807) |
| Ending balance                                                                                                                          | 23,102         |            |   |   | 26,703 |   |   |   | 23,102 | 26,703 | 37,919 |
| Consumer                                                                                                                                |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 2,593 |   |   |   | 2,902 | 2,593 | 2,902 | 3,622 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | (11) | 126 | (221) |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 556 | 695 | 942 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (623) | (1,130) | (1,441) |
| Ending balance                                                                                                                          | 2,515          |            |   |   | 2,593 |   |   |   | 2,515 | 2,593 | 2,902 |
| Residential                                                                                                                             |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 14,157 |   |   |   | 12,343 | 14,157 | 12,343 | 10,408 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | 3,514 | 6,176 | 8,166 |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 1,292 | 1,113 | 1,176 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (3,886) | (5,475) | (7,407) |
| Ending balance                                                                                                                          | 15,077         |            |   |   | 14,157 |   |   |   | 15,077 | 14,157 | 12,343 |
| Finance Leases                                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   |    |   |   |   | 3 |    | 3 | 98 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | 11 | 29 | (102) |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 4 | 2 | 7 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (15) | (34) |    |
| Ending balance                                                                                                                          |      |            |   |   |    |   |   |   |    |    | $ 3 |

| X                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Allowance for Loan and Lease Losses, Loan Recoveries
+ References
No definition available.
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| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.
+ References
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| 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
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| 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
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