Loans Receivable, Net - Aging of Recorded Investment in Past Due Loans Excluding PCI Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	$ 23,062	$ 16,767
Total Past Due	31,787	27,023
Loans Not Past Due	1,933,733	1,691,664
Total loans	1,965,520	1,718,687
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,843	8,329
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,882	1,927
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	4,322	1,619
Total Past Due	11,284	10,679
Loans Not Past Due	827,211	774,762
Total loans	838,495	785,441
Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,169	7,365
Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,793	1,695
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	17,057	12,758
Total Past Due	17,873	12,877
Loans Not Past Due	785,467	637,074
Total loans	803,340	649,951
Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	816	119
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	1,568	1,833
Total Past Due	2,515	2,910
Loans Not Past Due	191,791	196,439
Total loans	194,306	199,349
Consumer [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	858	845
Consumer [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	89	232
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	115	557
Total Past Due	115	557
Loans Not Past Due	129,264	83,389
Total loans	$ 129,379	$ 83,946