Loans and Allowance for Loan Losses - Schedule of Activity in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 55,461				$ 50,381	$ 55,461	$ 50,381	$ 49,808
Charge-offs									(14,789)	(12,969)	(12,717)
Recoveries									9,200	11,083	10,240
Provision	$ 1,264	$ 1,437	$ 1,003	1,043	$ 3,390	$ 750	$ 2,446	380	4,747	6,966	3,050
Ending balance	54,619				55,461				54,619	55,461	50,381
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				21,742				19,246	21,742	19,246	21,481
Charge-offs									(3,819)	(3,087)	(1,108)
Recoveries									1,650	1,519	2,281
Provision									3,012	4,064	(3,408)
Ending balance	22,585				21,742				22,585	21,742	19,246
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				23,470				21,436	23,470	21,436	18,173
Charge-offs									(2,846)	(879)	(3,700)
Recoveries									3,774	2,740	3,777
Provision									(2,810)	173	3,186
Ending balance	21,588				23,470				21,588	23,470	21,436
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				2,277				1,763	2,277	1,763	1,643
Charge-offs									(661)	(1,100)	(985)
Recoveries									146	2,118	255
Provision									537	(504)	850
Ending balance	2,299				2,277				2,299	2,277	1,763
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 7,972				$ 7,936	7,972	7,936	8,511
Charge-offs									(7,463)	(7,903)	(6,924)
Recoveries									3,630	4,706	3,927
Provision									4,008	3,233	2,422
Ending balance	$ 8,147				$ 7,972				$ 8,147	$ 7,972	$ 7,936