Loans Receivable, Net - Allowance for Loan Losses and Recorded Investment in Loans by Portfolio Segment and Based on Impairment Method (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Allowance for loan losses:
Balance at beginning of period	$ 20,930	$ 20,510
Provision (benefit) charged to operations	530	1,100
Charge-offs	(740)	(1,361)
Recoveries	214	245
Balance at end of period	20,934	20,494
Ending allowance balance attributed to loans:
Individually evaluated for impairment	3,938		3,647
Collectively evaluated for impairment	16,996		17,283
Total ending allowance balance	20,934		20,930
Loans:
Loans individually evaluated for impairment	41,662		39,903
Loans collectively evaluated for impairment	1,560,614		1,531,676
Total loans	1,602,276		1,571,579
Residential Real Estate [Member]
Allowance for loan losses:
Balance at beginning of period	4,859	5,241
Provision (benefit) charged to operations	(182)	830
Charge-offs	(590)	(950)
Recoveries	203	64
Balance at end of period	4,290	5,185
Ending allowance balance attributed to loans:
Individually evaluated for impairment	139		2
Collectively evaluated for impairment	4,151		4,857
Total ending allowance balance	4,290		4,859
Loans:
Loans individually evaluated for impairment	18,946		18,192
Loans collectively evaluated for impairment	766,400		763,214
Total loans	785,346		781,406
Commercial Real Estate [Member]
Allowance for loan losses:
Balance at beginning of period	10,371	8,937
Provision (benefit) charged to operations	1,034	324
Charge-offs
Recoveries	8	25
Balance at end of period	11,413	9,286
Ending allowance balance attributed to loans:
Individually evaluated for impairment	3,380		3,612
Collectively evaluated for impairment	8,033		6,759
Total ending allowance balance	11,413		10,371
Loans:
Loans individually evaluated for impairment	19,575		17,643
Loans collectively evaluated for impairment	531,233		511,302
Total loans	550,808		528,945
Consumer [Member]
Allowance for loan losses:
Balance at beginning of period	1,360	2,264
Provision (benefit) charged to operations	115	(94)
Charge-offs	(109)	(176)
Recoveries	3	154
Balance at end of period	1,369	2,148
Ending allowance balance attributed to loans:
Individually evaluated for impairment	419		33
Collectively evaluated for impairment	950		1,327
Total ending allowance balance	1,369		1,360
Loans:
Loans individually evaluated for impairment	2,865		2,961
Loans collectively evaluated for impairment	197,061		197,722
Total loans	199,926		200,683
Commercial and Industrial [Member]
Allowance for loan losses:
Balance at beginning of period	1,383	1,348
Provision (benefit) charged to operations	(298)	(21)
Charge-offs	(41)	(235)
Recoveries		2
Balance at end of period	1,044	1,094
Ending allowance balance attributed to loans:
Collectively evaluated for impairment	1,044		1,383
Total ending allowance balance	1,044		1,383
Loans:
Loans individually evaluated for impairment	276		1,107
Loans collectively evaluated for impairment	65,920		59,438
Total loans	66,196		60,545
Unallocated [Member]
Allowance for loan losses:
Balance at beginning of period	2,957	2,720
Provision (benefit) charged to operations	(139)	61
Balance at end of period	2,818	2,781
Ending allowance balance attributed to loans:
Collectively evaluated for impairment	2,818		2,957
Total ending allowance balance	$ 2,818		$ 2,957