Loans Receivable and Allowance for Loan Losses (Summary of Loans, Allowances and Impairment Balances, by Class and Impairment Method) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Allowance for loan losses:
Individually evaluated for impairment	$ 8,358	$ 3,630
Collectively evaluated for impairment	17,238	17,990
Total allowance for loan losses	25,596	21,620
Loans receivable:
Loans evaluated individually	64,172	63,504
Loans evaluated collectively	1,440,818	1,373,164
Total loans receivable	1,504,990	1,436,668
Period used to analyze future loan losses	2 years
Commercial and industrial [Member]
Allowance for loan losses:
Individually evaluated for impairment	4,161	1,000
Collectively evaluated for impairment	6,340	7,400
Total allowance for loan losses	10,501	8,400
Loans receivable:
Loans evaluated individually	18,734	15,504
Loans evaluated collectively	328,365	306,484
Total loans receivable	347,099	321,988
Commercial tax-exempt [Member]
Allowance for loan losses:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	80	79
Total allowance for loan losses	80	79
Loans receivable:
Loans evaluated individually	0	0
Loans evaluated collectively	88,934	81,532
Total loans receivable	88,934	81,532
Owner occupied real estate [Member]
Allowance for loan losses:
Individually evaluated for impairment	1,747	30
Collectively evaluated for impairment	664	699
Total allowance for loan losses	2,411	729
Loans receivable:
Loans evaluated individually	4,158	7,492
Loans evaluated collectively	270,077	271,880
Total loans receivable	274,235	279,372
Commercial construction and land development [Member]
Allowance for loan losses:
Individually evaluated for impairment	2,450	2,600
Collectively evaluated for impairment	5,144	5,240
Total allowance for loan losses	7,594	7,840
Loans receivable:
Loans evaluated individually	17,908	23,216
Loans evaluated collectively	89,403	79,937
Total loans receivable	107,311	103,153
Commercial real estate [Member]
Allowance for loan losses:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	3,223	3,241
Total allowance for loan losses	3,223	3,241
Loans receivable:
Loans evaluated individually	16,112	12,117
Loans evaluated collectively	377,070	352,288
Total loans receivable	393,182	364,405
Residential [Member]
Allowance for loan losses:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	344	435
Total allowance for loan losses	344	435
Loans receivable:
Loans evaluated individually	4,115	3,346
Loans evaluated collectively	78,874	80,594
Total loans receivable	82,989	83,940
Consumer [Member]
Allowance for loan losses:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	789	831
Total allowance for loan losses	789	831
Loans receivable:
Loans evaluated individually	3,145	1,829
Loans evaluated collectively	208,095	200,449
Total loans receivable	211,240	202,278
Unallocated [Member]
Allowance for loan losses:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	654	65
Total allowance for loan losses	654	65
Loans receivable:
Loans evaluated individually	0	0
Loans evaluated collectively	0	0
Total loans receivable	$ 0	$ 0