Loans Receivable, Net - Allowance for Loan Losses and Recorded Investment in Loans by Portfolio Segment and Based on Impairment Method Excluding PCI Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Allowance for loan losses:
Balance at beginning of period	$ 16,678	$ 16,534	$ 16,722	$ 16,317
Provision (benefit) charged to operations	888	300	2,113	975
Charge-offs	(2,116)	(211)	(3,511)	(900)
Recoveries	167	15	293	246
Balance at end of period	15,617	16,638	15,617	16,638
Ending allowance balance attributed to loans:
Individually evaluated for impairment	269		269		$ 1,339
Collectively evaluated for impairment	15,348		15,348		15,383
Total ending allowance balance	15,617		15,617		16,722
Loans:
Loans individually evaluated for impairment	34,907		34,907		38,372
Loans collectively evaluated for impairment	3,014,005		3,014,005		1,959,566
Total loans	3,048,912		3,048,912		1,997,938
Residential Real Estate [Member]
Allowance for loan losses:
Balance at beginning of period	6,006	3,610	6,590	4,291
Provision (benefit) charged to operations	(376)	1,602	(867)	920
Charge-offs	(167)	(51)	(319)	(174)
Recoveries	6		65	124
Balance at end of period	5,469	5,161	5,469	5,161
Ending allowance balance attributed to loans:
Individually evaluated for impairment	30		30		31
Collectively evaluated for impairment	5,439		5,439		6,559
Total ending allowance balance	5,469		5,469		6,590
Loans:
Loans individually evaluated for impairment	13,753		13,753		13,165
Loans collectively evaluated for impairment	1,094,089		1,094,089		828,841
Total loans	1,107,842		1,107,842		842,006
Commercial Real Estate - Owner Occupied [Member]
Allowance for loan losses:
Balance at beginning of period	2,711	3,716	2,292	3,627
Provision (benefit) charged to operations	(168)	(421)	1,261	(332)
Charge-offs			(1,010)
Balance at end of period	2,543	3,295	2,543	3,295
Ending allowance balance attributed to loans:
Individually evaluated for impairment					544
Collectively evaluated for impairment	2,543		2,543		1,748
Total ending allowance balance	2,543		2,543		2,292
Loans:
Loans individually evaluated for impairment	17,116		17,116		18,964
Loans collectively evaluated for impairment	474,002		474,002		288,545
Total loans	491,118		491,118		307,509
Commercial Real Estate - Investor [Member]
Allowance for loan losses:
Balance at beginning of period	4,713	5,513	4,873	5,308
Provision (benefit) charged to operations	104	(471)	(56)	(172)
Charge-offs				(103)
Recoveries		10		19
Balance at end of period	4,817	5,052	4,817	5,052
Ending allowance balance attributed to loans:
Individually evaluated for impairment	239		239		287
Collectively evaluated for impairment	4,578		4,578		4,586
Total ending allowance balance	4,817		4,817		4,873
Loans:
Loans individually evaluated for impairment	1,180		1,180		2,686
Loans collectively evaluated for impairment	1,013,431		1,013,431		508,039
Total loans	1,014,611		1,014,611		510,725
Consumer [Member]
Allowance for loan losses:
Balance at beginning of period	1,107	952	1,095	1,146
Provision (benefit) charged to operations	(130)	73	(98)	249
Charge-offs	(80)	(101)	(146)	(564)
Recoveries		3	46	96
Balance at end of period	897	927	897	927
Ending allowance balance attributed to loans:
Individually evaluated for impairment					43
Collectively evaluated for impairment	897		897		1,052
Total ending allowance balance	897		897		1,095
Loans:
Loans individually evaluated for impairment	2,589		2,589		2,307
Loans collectively evaluated for impairment	249,985		249,985		190,853
Total loans	252,574		252,574		193,160
Commercial and Industrial [Member]
Allowance for loan losses:
Balance at beginning of period	1,209	1,686	1,639	863
Provision (benefit) charged to operations	1,949	(101)	1,665	717
Charge-offs	(1,869)	(59)	(2,036)	(59)
Recoveries	161	2	182	7
Balance at end of period	1,450	1,528	1,450	1,528
Ending allowance balance attributed to loans:
Individually evaluated for impairment					434
Collectively evaluated for impairment	1,450		1,450		1,205
Total ending allowance balance	1,450		1,450		1,639
Loans:
Loans individually evaluated for impairment	269		269		1,250
Loans collectively evaluated for impairment	182,498		182,498		143,288
Total loans	182,767		182,767		144,538
Unallocated [Member]
Allowance for loan losses:
Balance at beginning of period	932	1,057	233	1,082
Provision (benefit) charged to operations	(491)	(382)	208	(407)
Balance at end of period	441	$ 675	441	$ 675
Ending allowance balance attributed to loans:
Collectively evaluated for impairment	441		441		233
Total ending allowance balance	$ 441		$ 441		$ 233