Non-interest Income and Expense - Components of Non Interest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Income and Expenses [Abstract]
Base salaries, net of deferred loan origination costs	$ 17,277	$ 17,211	$ 34,900	$ 33,968
Incentive compensation	2,395	3,706	5,496	6,273
Benefits and other compensation costs	7,383	5,802	13,931	11,606
Total salaries and benefits expense	27,055	26,719	54,327	51,847
Occupancy	3,398	3,738	7,273	7,512
Data processing and software	3,657	3,354	7,024	6,703
Equipment	1,350	1,752	2,862	3,619
Intangible amortization	1,431	1,431	2,862	2,862
Advertising	531	1,533	1,196	2,864
ATM and POS network charges	1,210	1,270	2,583	2,593
Professional fees	741	1,057	1,444	1,896
Telecommunications	639	773	1,364	1,570
Regulatory assessments and insurance	360	490	455	1,001
Postage	283	315	573	625
Operational losses	184	226	405	451
Courier service	337	412	668	682
Gain on sale of foreclosed assets	(16)	(99)	(57)	(198)
Loss on disposal of fixed assets	15	42	15	66
Other miscellaneous expense	4,530	3,684	7,530	8,056
Total other non-interest expense	18,650	19,978	36,197	40,302
Total non-interest expense	$ 45,705	$ 46,697	$ 90,524	$ 92,149