Loans Receivable and Allowance for Loan Losses - Impaired Loans by Class (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 20,497	$ 20,923	$ 21,718	$ 20,044
Impaired Financing Receivable, Interest Income, Accrual Method	72	187	216	365
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	1,759		1,759		676
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	1,822		1,822		1,160
Impaired Loans with a Specific Allowance, Related Allowance	203		203		613
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	12,599		12,599		24,659
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	17,375		17,375		27,349
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans with a Specific Allowance, Related Allowance	69		69		552
Commercial Real Estate [Member] | Owner-Occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	3,681	4,249	3,965	3,270
Impaired Financing Receivable, Interest Income, Accrual Method	1	41	9	99
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	0		0		615
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	0		0		1,099
Impaired Loans with a Specific Allowance, Related Allowance	0		0		552
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	3,160		3,160		3,947
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	4,345		4,345		4,575
Commercial Real Estate [Member] | Non-Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	7,361	3,980	7,205	3,605
Impaired Financing Receivable, Interest Income, Accrual Method	46	50	137	86
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	686		686		0
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	728		728		0
Impaired Loans with a Specific Allowance, Related Allowance	41		41		0
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	1,733		1,733		7,117
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	3,499		3,499		7,670
Commercial Real Estate [Member] | Multi - Family [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	98	168	234	89
Impaired Financing Receivable, Interest Income, Accrual Method	0	16	0	16
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	0		0		0
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	0		0		0
Impaired Loans with a Specific Allowance, Related Allowance	0		0		0
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	96		96		322
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	128		128		415
Commercial Real Estate [Member] | Non-Owner Occupied Residential [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	1,905	5,108	2,603	4,875
Impaired Financing Receivable, Interest Income, Accrual Method	0	45	2	60
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	222		222		0
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	243		243		0
Impaired Loans with a Specific Allowance, Related Allowance	28		28		0
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	1,418		1,418		4,493
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	1,846		1,846		4,836
Acquisition and Development [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans with a Specific Allowance, Related Allowance	0		0		0
Acquisition and Development [Member] | Commercial and Land Development [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	1,286	2,613	1,787	2,967
Impaired Financing Receivable, Interest Income, Accrual Method	9	0	20	2
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	0		0		0
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	0		0		0
Impaired Loans with a Specific Allowance, Related Allowance	0		0		0
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	1,249		1,249		3,177
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	1,929		1,929		3,812
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	1,263	1,875	1,676	1,724
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	2	65
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	0		0		0
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	0		0		0
Impaired Loans with a Specific Allowance, Related Allowance	0		0		0
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	694		694		2,001
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	766		766		2,143
Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Impaired Loans with a Specific Allowance, Related Allowance	134		134		61
Residential Mortgage [Member] | First Lien [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	4,772	2,421	4,068	2,528
Impaired Financing Receivable, Interest Income, Accrual Method	15	29	45	31
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	851		851		48
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	851		851		48
Impaired Loans with a Specific Allowance, Related Allowance	134		134		48
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	4,118		4,118		3,327
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	4,707		4,707		3,619
Residential Mortgage [Member] | Home Equity - Term [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	72	47	90	47
Impaired Financing Receivable, Interest Income, Accrual Method	0	2	0	2
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	0		0		13
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	0		0		13
Impaired Loans with a Specific Allowance, Related Allowance	0		0		13
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	72		72		94
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	73		73		96
Residential Mortgage [Member] | Home Equity - Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	49	116	85	336
Impaired Financing Receivable, Interest Income, Accrual Method	0	4	0	4
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	0		0		0
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	0		0		0
Impaired Loans with a Specific Allowance, Related Allowance	0		0		0
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	42		42		181
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	43		43		183
Installment and Other Loans [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	10	1	5	1
Impaired Financing Receivable, Interest Income, Accrual Method	1	0	1	0
Impaired Loans with a Specific Allowance, Recorded Investment (Book Balance)	0		0
Impaired Loans with a Specific Allowance, Unpaid Principal Balance (Legal Balance)	0		0
Impaired Loans with a Specific Allowance, Related Allowance	0		0		0
Impaired Loans with No Specific Allowance, Recorded Investment (Book Balance)	17		17
Impaired Loans with No Specific Allowance, Unpaid Principal Balance (Legal Balance)	$ 39		$ 39