Comprehensive Income - Components of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Before Tax Amount
Other comprehensive loss, net	$ 1,800	$ (2,807)	$ 15,065	$ (12,087)
Tax Benefit (Expense)
Other comprehensive loss, net	(398)	794	(4,017)	2,988
Net of Tax Amount
Other comprehensive income (loss)	1,402	(2,013)	11,048	(9,099)
Net unrealized gains (losses) on available for sale securities:
Before Tax Amount
Net unrealized holding gains (losses) arising during period	1,911	(2,816)	15,872	(12,521)
Reclassification adjustment for net gains arising during the period	0	0	0	0
Other comprehensive loss, net	1,911	(2,816)	15,872	(12,521)
Tax Benefit (Expense)
Net unrealized holding gains (losses) arising during period	(431)	797	(4,253)	3,080
Reclassification adjustment for net gains arising during the period	0	0	0	0
Other comprehensive loss, net	(431)	797	(4,253)	3,080
Net of Tax Amount
Net unrealized holding gains (losses) arising during period	1,480	(2,019)	11,619	(9,441)
Reclassification adjustment for net gains arising during the period	0	0	0	0
Other comprehensive income (loss)	1,480	(2,019)	11,619	(9,441)
Unrealized (losses) gains on derivatives
Before Tax Amount
Other comprehensive loss, net	(111)	9	(807)	434
Tax Benefit (Expense)
Other comprehensive loss, net	33	(3)	236	(92)
Net of Tax Amount
Other comprehensive income (loss)	$ (78)	$ 6	$ (571)	$ 342