Loans - Allowance for Loan Losses Disaggregated on the Basis of Impairment Methodology (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	$ 18,108		$ 20,596	$ 15,861
Loans collectively evaluated for impairment	80,178		71,842	77,539
Ending balance	98,286	95,156	92,438	93,400	93,589	104,453
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	16,500		16,682	11,330
Loans collectively evaluated for impairment	39,172		36,108	39,484
Ending balance	55,672	57,054	52,790	50,814	51,085	54,164
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	1,608		3,914	4,531
Loans collectively evaluated for impairment	20,438		18,676	19,042
Ending balance	22,046	21,020	22,590	23,573	24,809	29,346
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	0		0	0
Loans collectively evaluated for impairment	4,659		5,230	4,917
Ending balance	4,659	4,533	5,230	4,917	5,148	5,252
Consumer and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	0		0	0
Loans collectively evaluated for impairment	6,427		5,010	4,130
Ending balance	6,427	5,691	5,010	4,130	3,724	3,507
Unallocated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	0		0	0
Loans collectively evaluated for impairment	9,482		6,818	9,966
Ending balance	$ 9,482	$ 6,858	$ 6,818	$ 9,966	$ 8,823	$ 12,184