Loans Receivable, Net - Aging of Recorded Investment in Past Due Loans Excluding PCI Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 32,141	$ 39,728
Greater than 90 Days Past Due	10,758	9,573
Loans Not Past Due	5,906,312	5,540,084
Total loans	5,938,453	5,579,812
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	16,025	21,482
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,358	8,673
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,207	0
Greater than 90 Days Past Due	207	0
Loans Not Past Due	390,381	304,994
Total loans	391,588	304,994
Commercial and industrial | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,000	0
Commercial and industrial | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate – owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,241	5,537
Greater than 90 Days Past Due	1,577	197
Loans Not Past Due	764,489	734,838
Total loans	770,730	740,375
Commercial real estate – owner occupied | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,686	5,104
Commercial real estate – owner occupied | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,978	236
Commercial real estate – investor
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,133	8,943
Greater than 90 Days Past Due	4,024	2,461
Loans Not Past Due	2,122,629	2,006,267
Total loans	2,131,762	2,015,210
Commercial real estate – investor | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,579	3,979
Commercial real estate – investor | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	530	2,503
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	11,835	19,629
Greater than 90 Days Past Due	2,367	4,451
Loans Not Past Due	2,181,654	2,024,657
Total loans	2,193,489	2,044,286
Residential real estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,919	10,199
Residential real estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,549	4,979
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,725	5,619
Greater than 90 Days Past Due	2,583	2,464
Loans Not Past Due	447,159	469,328
Total loans	450,884	474,947
Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	841	2,200
Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 301	$ 955