Non-interest Income and Expense - Components of Noninterest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Income and Expenses [Abstract]
Base salaries, net of deferred loan origination costs									$ 69,844	$ 70,164	$ 70,218
Incentive compensation									14,957	10,022	13,106
Benefits and other compensation costs									21,550	31,935	22,741
Total salaries and benefits expense									106,351	112,121	106,065
Occupancy									14,910	14,528	14,893
Data processing and software									13,985	13,504	13,517
Equipment									5,358	5,704	7,022
ATM and POS network charges									6,040	5,433	5,447
Merger and acquisition expense									1,523	0	0
Advertising									2,899	2,827	5,633
Professional fees									3,657	3,222	3,754
Intangible amortization									5,464	5,724	5,723
Telecommunications									2,253	2,601	3,190
Regulatory assessments and insurance									2,581	1,594	1,188
Courier service									1,214	1,414	1,308
Operational losses									964	1,168	986
Postage									710	1,068	1,258
Gain on sale or acquisition of foreclosed assets									(233)	(235)	(246)
(Gain) loss on disposal of fixed assets									(439)	67	82
Other miscellaneous expense									11,038	12,018	15,637
Total other noninterest expense									71,924	70,637	79,392
Total noninterest expense	$ 46,679	$ 45,807	$ 44,171	$ 41,618	$ 45,745	$ 46,714	$ 45,550	$ 44,749	$ 178,275	$ 182,758	$ 185,457