Loans - Performing and Nonperforming Loans, Segregated by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	$ 594,562	$ 664,051
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	169,193	232,276
Commercial real estate: Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	15,625	16,863
Commercial real estate: Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	288,631	286,403
Residential: 1-4 family [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	73,104	78,557
Residential: Home equities [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	43,989	45,181
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	4,020	4,771
Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	558,696	625,478
Performing [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	161,692	229,341
Performing [Member] | Commercial real estate: Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	15,625	16,863
Performing [Member] | Commercial real estate: Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	271,736	262,395
Performing [Member] | Residential: 1-4 family [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	62,151	66,927
Performing [Member] | Residential: Home equities [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	43,472	45,181
Performing [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	4,020	4,771
Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	35,866	38,573
Nonperforming [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	7,501	2,935
Nonperforming [Member] | Commercial real estate: Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	0	0
Nonperforming [Member] | Commercial real estate: Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	16,895	24,008
Nonperforming [Member] | Residential: 1-4 family [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	10,953	11,630
Nonperforming [Member] | Residential: Home equities [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	517	0
Nonperforming [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross portfolio loans	$ 0	$ 0