Intangible Assets and Goodwill - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 32,313	$ 36,761
Accumulated Amortization	(14,107)	(17,762)
Net Carrying Amount	18,206	18,999
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	28,963	33,411
Accumulated Amortization	(11,366)	(15,076)
Net Carrying Amount	17,597	18,335
Customer Relationship Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,350	3,350
Accumulated Amortization	(2,741)	(2,686)
Net Carrying Amount	$ 609	$ 664