Loans Receivable and Allowance for Loan Losses - Activity in Allowance for Loan Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	$ 20,497	$ 21,917	$ 20,965	$ 23,166
Provision for loan losses	0	(1,400)	0	(1,400)
Charge-offs	(574)	(1,899)	(1,102)	(3,244)
Recoveries	502	1,480	562	1,576
Balance, end of period	20,425	20,098	20,425	20,098
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	13,719	12,165	13,215	13,719
Provision for loan losses	645	630	1,383	157
Charge-offs	(415)	(1,535)	(674)	(2,677)
Recoveries	104	28	129	89
Balance, end of period	14,053	11,288	14,053	11,288
Acquisition and Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	474	2,614	670	3,502
Provision for loan losses	407	(2,080)	211	(2,826)
Charge-offs	(34)	1	(34)	(144)
Recoveries	5	1,411	5	1,414
Balance, end of period	852	1,946	852	1,946
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	919	1,353	864	1,635
Provision for loan losses	(224)	(366)	(164)	(658)
Charge-offs	(55)	(114)	(64)	(114)
Recoveries	353	2	357	12
Balance, end of period	993	875	993	875
Municipal [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	244	285	244	223
Provision for loan losses	(66)	(31)	(66)	31
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Balance, end of period	178	254	178	254
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	15,356	16,417	14,993	19,079
Provision for loan losses	762	(1,847)	1,364	(3,296)
Charge-offs	(504)	(1,648)	(772)	(2,935)
Recoveries	462	1,441	491	1,515
Balance, end of period	16,076	14,363	16,076	14,363
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	3,112	3,388	3,780	2,275
Provision for loan losses	(741)	604	(1,222)	1,749
Charge-offs	(16)	(225)	(209)	(263)
Recoveries	7	29	13	35
Balance, end of period	2,362	3,796	2,362	3,796
Installment and Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	126	112	124	85
Provision for loan losses	81	38	125	69
Charge-offs	(54)	(26)	(121)	(46)
Recoveries	33	10	58	26
Balance, end of period	186	134	186	134
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	3,238	3,500	3,904	2,360
Provision for loan losses	(660)	642	(1,097)	1,818
Charge-offs	(70)	(251)	(330)	(309)
Recoveries	40	39	71	61
Balance, end of period	2,548	3,930	2,548	3,930
Unallocated [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Balance, beginning of period	1,903	2,000	2,068	1,727
Provision for loan losses	(102)	(195)	(267)	78
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Balance, end of period	$ 1,801	$ 1,805	$ 1,801	$ 1,805