Allowance for Loan Losses and Recorded Investment in Loans Receivable (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance			$ 4,367	$ 4,549	$ 4,549
Charge-offs			(651)		(1,041)
Recoveries			95		155
Provisions	500	195	500	630	704
Ending balance	4,312		4,312		4,367
Individually evaluated for impairment	20,699		20,699		25,847
Allowance for loan losses	2,135		2,135		2,385
Collectively evaluated for impairment	102,518		102,518		101,949
Allowance for loan losses	2,177		2,177		1,982
Ending balance	123,217		123,217		127,796
Total allowance for loan losses	4,312		4,312		4,367
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance			1,040	1,887	1,887
Charge-offs					(118)
Recoveries			3		52
Provisions					(781)
Ending balance	1,043		1,043		1,040
Individually evaluated for impairment	2,097		2,097		1,869
Allowance for loan losses	47		47		49
Collectively evaluated for impairment	7,023		7,023		7,155
Allowance for loan losses	996		996		991
Ending balance	9,120		9,120		9,024
Total allowance for loan losses	1,043		1,043		1,040
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance			1,675	1,920	1,920
Charge-offs			(299)		(339)
Recoveries			65		94
Provisions			400
Ending balance	1,841		1,841		1,675
Individually evaluated for impairment	11,839		11,839		16,661
Allowance for loan losses	1,273		1,273		1,260
Collectively evaluated for impairment	62,544		62,544		58,549
Allowance for loan losses	568		568		415
Ending balance	74,383		74,383		75,210
Total allowance for loan losses	1,841		1,841		1,675
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance			1,301	484	484
Charge-offs			(337)		(576)
Recoveries			22		5
Provisions			204		1,388
Ending balance	1,190		1,190		1,301
Individually evaluated for impairment	5,191		5,191		5,586
Allowance for loan losses	815		815		962
Collectively evaluated for impairment	25,221		25,221		28,212
Allowance for loan losses	375		375		339
Ending balance	30,412		30,412		33,798
Total allowance for loan losses	1,190		1,190		1,301
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance			351	258	258
Charge-offs			(15)		(8)
Recoveries			5		4
Provisions			(104)		97
Ending balance	238		238		351
Individually evaluated for impairment	1,572		1,572		1,731
Allowance for loan losses					114
Collectively evaluated for impairment	7,812		7,812		8,033
Allowance for loan losses	238		238		237
Ending balance	9,384		9,384		9,764
Total allowance for loan losses	$ 238		$ 238		$ 351