Loans - Allowance for Credit Losses and Recorded Investment in Financing Receivables (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Allowance for credit losses:
Allowance for credit losses, Beginning balance	$ 11,103	$ 10,622
Allowance for credit losses, Charge offs	(2,770)	(9,862)
Allowance for credit losses, Recoveries	3,089	943
Allowance for credit losses, Provision	2,750	9,400
Allowance for credit losses, Ending balance	14,172	11,103
Allowance for credit losses, Ending balance: individually evaluated for impairment	4,994	2,301
Allowance for credit losses, Ending balance: collectively evaluated for impairment	9,178	8,802
Financing receivables, Ending balance	597,995	664,051
Financing receivables, Ending balance individually evaluated for impairment	42,141	47,660
Financing receivables, Ending balance collectively evaluated for impairment	555,854	616,391
Commercial [Member]
Allowance for credit losses:
Allowance for credit losses, Beginning balance	4,168	2,773
Allowance for credit losses, Charge offs	(882)	(604)
Allowance for credit losses, Recoveries	58	118
Allowance for credit losses, Provision	3,713	1,881
Allowance for credit losses, Ending balance	7,057	4,168
Allowance for credit losses, Ending balance: individually evaluated for impairment	2,988	1,051
Allowance for credit losses, Ending balance: collectively evaluated for impairment	4,069	3,117
Financing receivables, Ending balance	170,429	232,276
Financing receivables, Ending balance individually evaluated for impairment	6,590	3,458
Financing receivables, Ending balance collectively evaluated for impairment	163,839	228,818
Commercial real estate [Member]
Allowance for credit losses:
Allowance for credit losses, Beginning balance	2,783	3,796
Allowance for credit losses, Charge offs	(230)	(6,541)
Allowance for credit losses, Recoveries	2,483	13
Allowance for credit losses, Provision	(2,252)	5,515
Allowance for credit losses, Ending balance	2,784	2,783
Allowance for credit losses, Ending balance: individually evaluated for impairment	814	194
Allowance for credit losses, Ending balance: collectively evaluated for impairment	1,970	2,589
Financing receivables, Ending balance	307,905	303,266
Financing receivables, Ending balance individually evaluated for impairment	21,747	29,077
Financing receivables, Ending balance collectively evaluated for impairment	286,158	274,189
Consumer [Member]
Allowance for credit losses:
Allowance for credit losses, Beginning balance	28	33
Allowance for credit losses, Charge offs	(25)	(5)
Allowance for credit losses, Recoveries	1	2
Allowance for credit losses, Provision	31	(2)
Allowance for credit losses, Ending balance	35	28
Allowance for credit losses, Ending balance: individually evaluated for impairment	0	0
Allowance for credit losses, Ending balance: collectively evaluated for impairment	35	28
Financing receivables, Ending balance	3,508	4,771
Financing receivables, Ending balance individually evaluated for impairment	0	0
Financing receivables, Ending balance collectively evaluated for impairment	3,508	4,771
Residential [Member]
Allowance for credit losses:
Allowance for credit losses, Beginning balance	3,335	3,690
Allowance for credit losses, Charge offs	(1,633)	(2,712)
Allowance for credit losses, Recoveries	547	810
Allowance for credit losses, Provision	244	1,547
Allowance for credit losses, Ending balance	2,493	3,335
Allowance for credit losses, Ending balance: individually evaluated for impairment	1,192	1,056
Allowance for credit losses, Ending balance: collectively evaluated for impairment	1,301	2,279
Financing receivables, Ending balance	116,153	123,738
Financing receivables, Ending balance individually evaluated for impairment	13,804	15,125
Financing receivables, Ending balance collectively evaluated for impairment	102,349	108,613
Unallocated [Member]
Allowance for credit losses:
Allowance for credit losses, Beginning balance	789	330
Allowance for credit losses, Charge offs	0	0
Allowance for credit losses, Recoveries	0	0
Allowance for credit losses, Provision	1,014	459
Allowance for credit losses, Ending balance	1,803	789
Allowance for credit losses, Ending balance: individually evaluated for impairment	0	0
Allowance for credit losses, Ending balance: collectively evaluated for impairment	1,803	789
Financing receivables, Ending balance	0	0
Financing receivables, Ending balance individually evaluated for impairment	0	0
Financing receivables, Ending balance collectively evaluated for impairment	$ 0	$ 0