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
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Allowance for loan losses:
Balance at beginning of period	$ 16,722	$ 16,317
Provision (benefit) charged to operations	563	375
Charge-offs	(1,172)	(358)
Recoveries	101	85
Balance at end of period	16,214	16,419
Ending allowance balance attributed to loans:
Individually evaluated for impairment	249		$ 1,339
Collectively evaluated for impairment	15,965		15,383
Total ending allowance balance	16,214		16,722
Loans:
Loans individually evaluated for impairment	34,443		38,372
Loans collectively evaluated for impairment	1,990,168		1,959,566
Total loans	2,024,611		1,997,938
Residential Real Estate [Member]
Allowance for loan losses:
Balance at beginning of period	6,590	4,291
Provision (benefit) charged to operations	(11)	(52)
Charge-offs	(78)	(55)
Recoveries	54	22
Balance at end of period	6,555	4,206
Ending allowance balance attributed to loans:
Individually evaluated for impairment	43		31
Collectively evaluated for impairment	6,512		6,559
Total ending allowance balance	6,555		6,590
Loans:
Loans individually evaluated for impairment	13,530		13,165
Loans collectively evaluated for impairment	833,482		828,841
Total loans	847,012		842,006
Commercial Real Estate - Owner Occupied [Member]
Allowance for loan losses:
Balance at beginning of period	2,292	3,627
Provision (benefit) charged to operations	1,039	202
Charge-offs	(968)
Balance at end of period	2,363	3,829
Ending allowance balance attributed to loans:
Individually evaluated for impairment	127		544
Collectively evaluated for impairment	2,236		1,748
Total ending allowance balance	2,363		2,292
Loans:
Loans individually evaluated for impairment	17,226		18,964
Loans collectively evaluated for impairment	291,440		288,545
Total loans	308,666		307,509
Commercial Real Estate - Investor [Member]
Allowance for loan losses:
Balance at beginning of period	4,873	5,308
Provision (benefit) charged to operations	(581)	251
Charge-offs		(88)
Recoveries	10
Balance at end of period	4,302	5,471
Ending allowance balance attributed to loans:
Individually evaluated for impairment	79		287
Collectively evaluated for impairment	4,223		4,586
Total ending allowance balance	4,302		4,873
Loans:
Loans individually evaluated for impairment	925		2,686
Loans collectively evaluated for impairment	535,622		508,039
Total loans	536,547		510,725
Consumer [Member]
Allowance for loan losses:
Balance at beginning of period	1,095	1,146
Provision (benefit) charged to operations	(40)	72
Charge-offs	(3)	(215)
Recoveries	29	60
Balance at end of period	1,081	1,063
Ending allowance balance attributed to loans:
Individually evaluated for impairment			43
Collectively evaluated for impairment	1,081		1,052
Total ending allowance balance	1,081		1,095
Loans:
Loans individually evaluated for impairment	2,059		2,307
Loans collectively evaluated for impairment	189,132		190,853
Total loans	191,191		193,160
Commercial and Industrial [Member]
Allowance for loan losses:
Balance at beginning of period	1,639	863
Provision (benefit) charged to operations	(144)	(99)
Charge-offs	(123)
Recoveries	8	3
Balance at end of period	1,380	767
Ending allowance balance attributed to loans:
Individually evaluated for impairment			434
Collectively evaluated for impairment	1,380		1,205
Total ending allowance balance	1,380		1,639
Loans:
Loans individually evaluated for impairment	703		1,250
Loans collectively evaluated for impairment	140,492		143,288
Total loans	141,195		144,538
Unallocated [Member]
Allowance for loan losses:
Balance at beginning of period	233	1,082
Provision (benefit) charged to operations	300	1
Balance at end of period	533	$ 1,083
Ending allowance balance attributed to loans:
Collectively evaluated for impairment	533		233
Total ending allowance balance	$ 533		$ 233