Loans Receivable, Net - Components of Loans Receivable, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 3,848,923	$ 3,821,886
Purchased credit impaired ("PCI") loans	7,118	7,575
Total Loans	3,856,041	3,829,461
Loans in process	(17,976)	(14,249)
Deferred origination costs, net	3,686	3,414
Allowance for loan losses	(16,151)	(15,183)	$ (16,214)	$ (16,722)
Total loans, net	3,825,600	3,803,443
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,848,904	1,818,858
Commercial | Commercial And Industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	205,590	152,569
Commercial | Commercial Real Estate - Owner Occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	531,325	534,214
Commercial | Commercial Real Estate - Investor
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,111,989	1,132,075
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	2,000,019	2,003,028
Allowance for loan losses	(1,136)	(1,110)	$ (1,081)	$ (1,095)
Consumer | Residential Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,636,497	1,647,154
Consumer | Residential Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	76,985	65,319
Consumer | Home Equity Loans and Lines
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	285,149	288,991
Consumer | Other Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 1,388	$ 1,564