Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive (Loss) Income by Component Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized holding gain (loss) on available-for-sale securities arising during the period, Pretax	$ 617	$ 762	$ 1,157	$ 1,511
Beginning balance, After-tax			72
Other comprehensive income	500	614	938	1,218
Ending Balance, After-tax	1,010		1,010
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Pretax	646	(1,022)	92	(1,786)
Unrealized holding gain (loss) on available-for-sale securities arising during the period, Pretax	617	762	1,157	1,511
Amortization of held-to-maturity discount resulting from transfer, Pretax	16	15	30	30
Total other comprehensive income (loss), Pretax	633	777	1,187	1,541
Ending balance, Pretax	1,279	(245)	1,279	(245)
Beginning balance, Tax Effect	(136)	214	(20)	374
Unrealized holding gain (loss) on available-for-sale securities arising during the period, Tax Effect	(130)	(160)	(243)	(317)
Amortization of held-to-maturity discount resulting from transfer, Tax Effect	(3)	(3)	(6)	(6)
Total other comprehensive income (loss), Tax Effect	(133)	(163)	(249)	(323)
Ending Balance, Tax Effect	(269)	51	(269)	51
Beginning balance, After-tax	510	(808)	72	(1,412)
Unrealized holding gain (loss) on available-for-sale securities arising during the period, After-Tax	487	602	914	1,194
Amortization of held-to-maturity discount resulting from transfer, After-tax	13	12	24	24
Other comprehensive income	500	614	938	1,218
Ending Balance, After-tax	$ 1,010	$ (194)	$ 1,010	$ (194)