| **Fair Values of Assets and Liabilities - Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)In Thousands, unless otherwise specified** | 3 Months Ended | 9 Months Ended |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                    |           |           |   |   |
| Balance, beginning of period                                                                                                                                                                         | $ 27,289       | $ 23,212       | $ 24,793 | $ 37,812 |
| Total gains or losses included in earnings                                                                                                                                                           | 242            | 0              | 625 | 2,409 |
| Total gains or losses included in other comprehensive income                                                                                                                                         | 1,716          | 2,030          | 7,399 | 3,610 |
| Purchases                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Issuances                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Sales                                                                                                                                                                                                | 242            | 0              | (20,760) | (15,981) |
| Settlements                                                                                                                                                                                          | 2,128          | 771            | (5,315) | (3,840) |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3                                                                                    |           | 0              |   |   |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3                                                                                       | 0              |           | 20,135 | 461 |
| Balance, end of period                                                                                                                                                                               | 26,877         | 24,471         | 26,877 | 24,471 |
| Pooled Trust Preferred Collateralized Debt Obligations [Member]                                                                                                                                      |           |           |   |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                    |           |           |   |   |
| Balance, beginning of period                                                                                                                                                                         | 25,869         | 21,792         | 23,373 | 22,980 |
| Total gains or losses included in earnings                                                                                                                                                           | 0              | 0              | 0 | 0 |
| Total gains or losses included in other comprehensive income                                                                                                                                         | 1,716          | 2,030          | 7,399 | 3,610 |
| Purchases                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Issuances                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Sales                                                                                                                                                                                                | 0              | 0              | 0 | 0 |
| Settlements                                                                                                                                                                                          | 2,128          | 771            | (5,315) | (3,539) |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3                                                                                    |           | 0              |   |   |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3                                                                                       | 0              |           | 0 | 0 |
| Balance, end of period                                                                                                                                                                               | 25,457         | 23,051         | 25,457 | 23,051 |
| Equity Securities [Member]                                                                                                                                                                           |           |           |   |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                    |           |           |   |   |
| Balance, beginning of period                                                                                                                                                                         | 1,420          | 1,420          | 1,420 | 1,420 |
| Total gains or losses included in earnings                                                                                                                                                           | 0              | 0              | 0 | 0 |
| Total gains or losses included in other comprehensive income                                                                                                                                         | 0              | 0              | 0 | 0 |
| Purchases                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Issuances                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Sales                                                                                                                                                                                                | 0              | 0              | 0 | 0 |
| Settlements                                                                                                                                                                                          | 0              | 0              | 0 | 0 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3                                                                                    |           | 0              |   |   |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3                                                                                       | 0              |           | 0 | 0 |
| Balance, end of period                                                                                                                                                                               | 1,420          | 1,420          | 1,420 | 1,420 |
| Loans Held For Sale [Member]                                                                                                                                                                         |           |           |   |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                    |           |           |   |   |
| Balance, beginning of period                                                                                                                                                                         | 0              | 0              | 0 | 13,412 |
| Total gains or losses included in earnings                                                                                                                                                           | 242            | 0              | 625 | 2,870 |
| Total gains or losses included in other comprehensive income                                                                                                                                         | 0              | 0              | 0 | 0 |
| Purchases                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Issuances                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Sales                                                                                                                                                                                                | 242            | 0              | (20,760) | (15,981) |
| Settlements                                                                                                                                                                                          | 0              | 0              | 0 | (301) |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3                                                                                    |           | 0              |   |   |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3                                                                                       | 0              |           | 20,135 | 0 |
| Balance, end of period                                                                                                                                                                               | 0              | 0              | 0 | 0 |
| Other Assets [Member]                                                                                                                                                                                |           |           |   |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                    |           |           |   |   |
| Balance, beginning of period                                                                                                                                                                         | 0              | 0              | 0 | 0 |
| Total gains or losses included in earnings                                                                                                                                                           | 0              | 0              | 0 | (461) |
| Total gains or losses included in other comprehensive income                                                                                                                                         | 0              | 0              | 0 | 0 |
| Purchases                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Issuances                                                                                                                                                                                            | 0              | 0              | 0 | 0 |
| Sales                                                                                                                                                                                                | 0              | 0              | 0 | 0 |
| Settlements                                                                                                                                                                                          | 0              | 0              | 0 | 0 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3                                                                                    |           | 0              |   |   |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3                                                                                       | 0              |           | 0 | 461 |
| Balance, end of period                                                                                                                                                                               | $ 0            | $ 0            | $ 0 | $ 0 |

| X                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Issues that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Sales that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Transfers out of assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -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.
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