Loans Receivable, Net - Components of Loans Receivable, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 3,898,617		$ 3,821,886
Purchased credit impaired ("PCI") loans	4,969		7,575
Total Loans	3,903,586		3,829,461
Loans in process	(22,589)		(14,249)
Deferred origination costs, net	4,365		3,414
Allowance for loan losses	(16,557)	$ (16,151)	(15,183)	$ (16,678)	$ (16,214)	$ (16,722)
Total loans, net	3,868,805		3,803,443
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,870,747		1,818,858
Commercial | Commercial And Industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	193,625		152,569
Commercial | Commercial Real Estate - Owner Occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	556,180		534,214
Commercial | Commercial Real Estate - Investor
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,120,942		1,132,075
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	2,027,870		2,003,028
Allowance for loan losses	(930)	$ (1,136)	(1,110)	$ (1,107)	$ (1,081)	$ (1,095)
Consumer | Residential Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,665,862		1,647,154
Consumer | Residential Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	78,339		65,319
Consumer | Home Equity Loans and Lines
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	282,402		288,991
Consumer | Other Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 1,267		$ 1,564