Goodwill and Other Intangible Assets - Schedule of Change in Loan Servicing Rights (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Balance at beginning of year	$ 24,193	$ 22,084	$ 20,368
Origination of loan servicing rights	7,473	8,216	7,039
Amortization expense	(6,934)	(6,107)	(5,323)
Balance at end of year	24,732	24,193	22,084
Balance at beginning of year	(83)	(471)	(900)
Impairment adjustment	36	388	429
Balance at end of year	(47)	(83)	(471)
Balance at end of year, net of valuation allowance	$ 24,685	$ 24,110	$ 21,613