| Borrowings - Summary of Financial Data Pertaining to Federal Home Loan Bank Advances (Detail) - USD ($) | 3 Months Ended | 12 Months Ended | 
|---|---|---|
| Mar. 31, 2020 | Dec. 31, 2019 | |
| Federal Home Loan Banks [Abstract] | ||
| Weighted-average interest rate at end of period | 0.92% | 1.70% | 
| Weighted-average interest rate during the period | 1.52% | 1.89% | 
| Average balance of FHLB advances | $ 130,659,000 | $ 40,374,000 | 
| Maximum amount outstanding at any month-end | $ 300,000,000 | $ 285,000,000 | 
| X | ||||||||||
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- Definition The calculated average balance outstanding for the year for all Federal Home Loan Bank advances as of the Balance Sheet date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition The calculated weighted average interest rate for Federal Home Loan Bank advances outstanding as of the Balance Sheet date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
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- Definition The calculated weighted average interest rate for Federal Home Loan Bank advances for the period ended as of the Balance Sheet date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition The maximum balance outstanding at any month end during the period as of the Balance Sheet date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- References No definition available. 
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