Revenue Recognition - Summary of Company's Source of Non-interest Income (Parenthetical) (Detail) - Other [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue From Contract With Customer [Line Items]
Recovery on zero-basis purchased loans, income from equity method investments	$ 118	$ 58
Accounting Standards Update 2014-09 [Member]
Revenue From Contract With Customer [Line Items]
Investment referral income, insurance sales commissions and other non-interest income related to loans and deposits	$ 734	$ 403