Non-interest Income and Expense - Components of Non Interest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Income and Expenses [Abstract]
Base salaries, net of deferred loan origination costs	$ 17,673	$ 18,754	$ 50,721	$ 53,654
Incentive compensation	3,123	2,184	11,025	7,680
Benefits and other compensation costs	5,478	8,383	16,939	22,314
Total salaries and benefits expense	26,274	29,321	78,685	83,648
Occupancy	3,771	3,440	11,197	10,713
Data processing and software	3,689	3,561	10,092	10,585
Equipment	1,336	1,549	4,060	4,411
Intangible amortization	1,409	1,431	4,271	4,293
Advertising	966	869	2,080	2,065
ATM and POS network charges	1,692	1,314	4,489	3,897
Professional fees	1,090	955	2,730	2,399
Telecommunications	574	619	1,719	1,983
Regulatory assessments and insurance	673	538	1,903	993
Merger and acquisition expense	651	0	651	0
Postage	156	118	478	691
Operational losses	244	154	665	559
Courier service	286	345	868	1,013
Gain on sale or acquisition of foreclosed assets	(144)	0	(210)	(57)
(Gain) loss on disposal of fixed assets	(19)	22	(445)	37
Other miscellaneous expense	3,159	2,478	8,363	9,783
Total other non-interest expense	19,533	17,393	52,911	53,365
Total non-interest expense	$ 45,807	$ 46,714	$ 131,596	$ 137,013