Loans Receivable, Net - Components of Loans Receivable, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 3,048,912		$ 1,997,938
Purchased credit impaired ("PCI") loans	5,836		461
Total Loans	3,054,748		1,998,399
Loans in process	(13,842)		(14,206)
Deferred origination costs, net	3,407		3,232
Allowance for loan losses	(15,617)	$ (16,678)	(16,722)	$ (16,638)	$ (16,534)	$ (16,317)
Total loans, net	3,028,696		1,970,703
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,688,496		962,772
Commercial [Member] | Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	182,767		144,538
Commercial [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	491,118		307,509
Commercial [Member] | Commercial Real Estate - Investor [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,014,611		510,725
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,360,416		1,035,166
Allowance for loan losses	(897)	$ (1,107)	(1,095)	$ (927)	$ (952)	$ (1,146)
Consumer [Member] | Residential Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,061,029		791,249
Consumer [Member] | Residential Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	46,813		50,757
Consumer [Member] | Home Equity Loans and Lines [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	251,304		192,368
Consumer [Member] | Other Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 1,270		$ 792