| **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                                                                                                                       |           |            |   | $ 70,898 |   |   |   | $ 82,977 | $ 70,898 | $ 82,977 | $ 92,131 |
| Provision for losses                                                                                                                    | 4,505          | 4,609           | 4,545 | 4,875 | 5,855 | 5,556 | 5,625 | 5,594 | 18,534 | 22,630 | 46,483 |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 7,206 | 13,764 | 11,935 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (27,272) | (48,473) | (67,572) |
| Ending balance                                                                                                                          | 69,366         |            |   |   | 70,898 |   |   |   | 69,366 | 70,898 | 82,977 |
| Commercial                                                                                                                              |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 17,731 |   |   |   | 32,508 | 17,731 | 32,508 | 48,770 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | 14,749 | (13,787) | (180) |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 1,744 | 8,828 | 6,750 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (8,311) | (9,818) | (22,832) |
| Ending balance                                                                                                                          | 25,913         |            |   |   | 17,731 |   |   |   | 25,913 | 17,731 | 32,508 |
| Real Estate Commercial                                                                                                                  |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 37,919 |   |   |   | 36,341 | 37,919 | 36,341 | 30,189 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | (2,546) | 28,574 | 37,555 |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 3,652 | 2,811 | 1,420 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (12,322) | (29,807) | (32,823) |
| Ending balance                                                                                                                          | 26,703         |            |   |   | 37,919 |   |   |   | 26,703 | 37,919 | 36,341 |
| Consumer                                                                                                                                |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 2,902 |   |   |   | 3,622 | 2,902 | 3,622 | 2,242 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | 126 | (221) | 2,868 |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 695 | 942 | 938 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (1,130) | (1,441) | (2,426) |
| Ending balance                                                                                                                          | 2,593          |            |   |   | 2,902 |   |   |   | 2,593 | 2,902 | 3,622 |
| Residential                                                                                                                             |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 12,343 |   |   |   | 10,408 | 12,343 | 10,408 | 10,751 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | 6,176 | 8,166 | 6,267 |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 1,113 | 1,176 | 2,827 |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (5,475) | (7,407) | (9,437) |
| Ending balance                                                                                                                          | 14,157         |            |   |   | 12,343 |   |   |   | 14,157 | 12,343 | 10,408 |
| Finance Leases                                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| **Allowance for loan losses:**                                                                                                          |           |            |   |   |   |   |   |   |   |   |   |
| Beginning balance                                                                                                                       |           |            |   | 3 |   |   |   | 98 | 3 | 98 | 179 |
| Provision for losses                                                                                                                    |           |            |   |   |   |   |   |   | 29 | (102) | (27) |
| Recoveries on loans                                                                                                                     |           |            |   |   |   |   |   |   | 2 | 7 |    |
| Loans charged off                                                                                                                       |           |            |   |   |   |   |   |   | (34) |    | (54) |
| Ending balance                                                                                                                          |           |            |   |   | $ 3 |   |   |   |   | $ 3 | $ 98 |

| X                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Allowance for Loan and Lease Losses, Loan Recoveries
+ References
No definition available.
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| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reflects the amount of loans and leases that have been removed, or charged off, from both loan receivables and the reserve for credit losses, typically because they are considered to be not salvageable or have been purchased by unconsolidated collection entities.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 114 -Paragraph 20 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5212-111524Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9
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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
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 8, 9 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: 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 3: 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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher OTS -Name Federal Regulation (FR) -Number Title 12 -Section 563c.102 -Paragraph 8 -Subparagraph a(ii) -Chapter V -Subsection I -LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy.  It will be removed from future versions of this taxonomy.Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 114 -Paragraph 20 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section L -Subsection 1
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| - Definition
The sum of the periodic provision charged to earnings, based on an assessment of uncollectibility from the counterparty on account of loan, lease or other credit losses, to reduce these accounts to the amount that approximates their net realizable value.
+ References
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