| **Fair Values of Assets and Liabilities - Additional Information (Detail) (USD $)**                                              | 3 Months Ended | 9 Months Ended |              |
|----------------------------------------------------------------------------------------------------------------------------------|----------------|----------------|--------------|
||
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]**                               |           |           |         |   |   |
| Credit loss on interest rate swap                                                                                                |           |           | $ 900,000    |   |   |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3                |           | 0              |         |   |   |
| Fair Value, Assets, Level 1 to Level 2 Transfers, Description                                                                    | 0.000          | 0.000          | 0.000        | 0.000 |   |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3                   | 0              |           | 20,135,000   | 461,000 |   |
| Impaired loans considered to be credit risk of non-collection                                                                    | 100,000        |           | 100,000      |   |   |
| Updated appraisal requirement floor                                                                                              | 250,000        |           | 250,000      |   |   |
| Other real estate owned                                                                                                          | 9,656,000      |           | 9,656,000    |   | 11,262,000 |
| Financial instrument of credit risk                                                                                              | 100,000        |           | 100,000      |   | 200,000 |
| Fair Value, Assets Measured on Recurring Basis, Gain (Loss) Included in Other Income, Assets and Liabilities Continue to be held | 0              | 0              | 0            | 0 |   |
| Other Assets [Member]                                                                                                            |           |           |         |   |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]**                               |           |           |         |   |   |
| 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            | 461,000 |   |
| Loans Held For Sale [Member]                                                                                                     |           |           |         |   |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]**                               |           |           |         |   |   |
| 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            |           | $ 20,135,000 | $ 0 |   |
| Minimum [Member]                                                                                                                 |           |           |         |   |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]**                               |           |           |         |   |   |
| Swap Rates Term Used to Determine Yield Curve                                                                                    | 3 years        |           | 3 years      |   |   |
| Maximum [Member]                                                                                                                 |           |           |         |   |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]**                               |           |           |         |   |   |
| Swap Rates Term Used to Determine Yield Curve                                                                                    | 30 years       |           | 30 years     |   |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair Value, Assets Measured on Recurring Basis, Gain (Loss) Included in Other Income, Assets and Liabilities Continue to be held
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Impaired loans fair value non collection.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Swap Rates Term Used to Determine Yield Curve
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| X                                                                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Updated appraisal requirement floor.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents disclosure of all significant concentrations of credit risk or market risk arising from the subject financial instrument (as defined), whether from an individual counterparty or groups of counterparties.
+ 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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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate loss on all derivative instruments charged against earnings during the period, before tax effects.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.
+ References
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