Loans and Allowance for Loan Losses - Schedule of Activity in Troubled Debt Restructurings (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Financing Receivable, Impaired [Line Items]
Beginning balance	$ 40,716	$ 44,251
(Charge-offs)/recoveries	199	(615)
Payments	(13,033)	(15,741)
Additions	29,733	22,534
Interest collected on nonaccrual loans	2,792	1,424
Ending balance	60,407	51,853
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Beginning balance	16,802	23,354
(Charge-offs)/recoveries	(64)	(742)
Payments	(8,526)	(10,819)
Additions	9,442	11,233
Interest collected on nonaccrual loans	2,410	1,251
Ending balance	20,064	24,277
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Beginning balance	18,327	14,602
(Charge-offs)/recoveries	360	108
Payments	(3,423)	(4,035)
Additions	17,429	10,581
Interest collected on nonaccrual loans	366	173
Ending balance	33,059	21,429
Residential [Member]
Financing Receivable, Impaired [Line Items]
Beginning balance	2,985	2,693
(Charge-offs)/recoveries		42
Payments	(283)	(462)
Additions	938	335
Ending balance	3,640	2,608
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Beginning balance	2,602	3,602
(Charge-offs)/recoveries	(97)	(23)
Payments	(801)	(425)
Additions	1,924	385
Interest collected on nonaccrual loans	16
Ending balance	$ 3,644	$ 3,539