Fair Value Measurements - Assets Measured at Fair Value (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Securities AFS [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Fair Value	$ 13,301	$ 88,728
Valuation Technique	Discounted cash flow	Discounted cash flow
Unobservable Input	Discount rate	Discount rate
Impaired Loans [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Fair Value	$ 877	$ 251
Valuation Technique	Appraisal of collateral	Appraisal of collateral
Unobservable Input	Appraisal adjustments	Appraisal adjustments
Other Real Estate Owned [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Fair Value		$ 2,225
Valuation Technique		Appraisal of collateral
Unobservable Input		Appraisal adjustments
Unobservable Input Value or Range		30.00%
Minimum [Member] | Securities AFS [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities AFS, Unobservable Input Value or Range	1.5	2.1
Minimum [Member] | Impaired Loans [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Impaired Loans, Unobservable Input Value or Range	0	0
Maximum [Member] | Securities AFS [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities AFS, Unobservable Input Value or Range	3.2	4.1
Maximum [Member] | Impaired Loans [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Impaired Loans, Unobservable Input Value or Range	30	30