| Goodwill and Other Intangibles - Additional Information (Detail) - USD ($) | 3 Months Ended | ||
|---|---|---|---|
| Oct. 27, 2016 | Aug. 31, 2014 | Mar. 31, 2020 | |
| Finite-Lived Intangible Assets [Line Items] | |||
| Intangible assets amortization expense | $ 65,000 | ||
| CBI Merger | |||
| Finite-Lived Intangible Assets [Line Items] | |||
| Goodwill | $ 11,000,000.0 | ||
| CBI Merger | Third-party originators intangible | |||
| Finite-Lived Intangible Assets [Line Items] | |||
| Intangible assets acquired | $ 483,000 | ||
| CBI Merger | Core deposit intangible | |||
| Finite-Lived Intangible Assets [Line Items] | |||
| Intangible assets acquired | $ 2,200,000 | 
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- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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