Comprehensive Income - Components of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Before Tax Amount
Other comprehensive income net	$ 9,797	$ 3,278	$ (8,773)	$ 12,254
Tax Benefit (Expense)
Other comprehensive income net	(2,761)	(802)	2,721	(3,085)
Net of Tax Amount
Other comprehensive (loss) income before classifications			(6,052)	9,423
Reclassification adjustment for net gains arising during the period			0	(254)
Other comprehensive income, net of tax	7,036	2,476	(6,052)	9,169
Net unrealized gains (losses) on available for sale securities:
Before Tax Amount
Net unrealized holding gains arising during period	9,729	3,329	(8,908)	13,124
Reclassification adjustment for net gains arising during the period	0	0	0	(342)
Other comprehensive income net	9,729	3,329	(8,908)	12,782
Tax Benefit (Expense)
Net unrealized holding gains arising during period	(2,616)	(817)	2,886	(3,328)
Reclassification adjustment for net gains arising during the period	0	0	0	88
Other comprehensive income net	(2,616)	(817)	2,886	(3,240)
Net of Tax Amount
Other comprehensive (loss) income before classifications	7,113	2,512	(6,022)	9,796
Reclassification adjustment for net gains arising during the period	0	0	0	(254)
Other comprehensive income, net of tax	7,113	2,512	(6,022)	9,542
Unrealized gains (losses) on derivatives
Before Tax Amount
Other comprehensive income net	68	(51)	135	(528)
Tax Benefit (Expense)
Other comprehensive income net	(145)	15	(165)	155
Net of Tax Amount
Other comprehensive (loss) income before classifications			(30)	(373)
Reclassification adjustment for net gains arising during the period			0	0
Other comprehensive income, net of tax	$ (77)	$ (36)	$ (30)	$ (373)