Loans Receivable, Net - Aging of Recorded Investment in Past Due Loans Excluding PCI Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	$ 16,076	$ 10,917
Total Past Due	36,362	36,165
Loans Not Past Due	3,812,561	3,785,721
Total loans	3,848,923	3,821,886
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	12,354	20,561
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,932	4,687
Residential Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	8,343	7,159
Total Past Due	17,317	19,729
Loans Not Past Due	1,696,165	1,692,744
Total loans	1,713,482	1,712,473
Residential Real Estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,875	9,532
Residential Real Estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,099	3,038
Commercial Real Estate - Owner Occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	1,406	890
Total Past Due	5,246	5,884
Loans Not Past Due	526,079	528,330
Total loans	531,325	534,214
Commercial Real Estate - Owner Occupied | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,224	3,962
Commercial Real Estate - Owner Occupied | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	616	1,032
Commercial Real Estate - Investor
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	4,492	521
Total Past Due	8,038	521
Loans Not Past Due	1,103,951	1,131,554
Total loans	1,111,989	1,132,075
Commercial Real Estate - Investor | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	970	0
Commercial Real Estate - Investor | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,576	0
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	1,513	1,963
Total Past Due	3,336	3,918
Loans Not Past Due	283,201	286,637
Total loans	286,537	290,555
Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,351	1,519
Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	472	436
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Greater than 90 Days Past Due	322	384
Total Past Due	2,425	6,113
Loans Not Past Due	203,165	146,456
Total loans	205,590	152,569
Commercial and Industrial | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,934	5,548
Commercial and Industrial | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 169	$ 181