Loans Receivable and Allowance for Loan Losses (Summary of Allowances on Loans Receivable, by Class) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	$ 28,038	$ 26,158	$ 25,282	$ 21,620
Provision charged to operating expenses	1,200	2,500	5,300	7,950
Recoveries of loans previously charged-off	610	157	1,504	891
Loans charged-off	(2,423)	(3,219)	4,661	(4,865)
Allowance for loan losses, ending	27,425	25,596	27,425	25,596
Commercial and industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	10,549	10,575	9,959	8,400
Provision charged to operating expenses	(437)	398	1,085	2,832
Recoveries of loans previously charged-off	613	15	945	216
Loans charged-off	(1,462)	(487)	(2,726)	(947)
Allowance for loan losses, ending	9,263	10,501	9,263	10,501
Commercial tax-exempt [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	74	74	83	79
Provision charged to operating expenses	1	6	(8)	1
Recoveries of loans previously charged-off	0	0	0	0
Loans charged-off	0	0	0	0
Allowance for loan losses, ending	75	80	75	80
Owner occupied real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	2,207	2,117	2,129	729
Provision charged to operating expenses	4	294	315	1,766
Recoveries of loans previously charged-off	0	0	3	8
Loans charged-off	(34)	0	(270)	(92)
Allowance for loan losses, ending	2,177	2,411	2,177	2,411
Commercial construction and land development [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	7,810	8,917	7,222	7,840
Provision charged to operating expenses	(33)	(762)	82	464
Recoveries of loans previously charged-off	(21)	64	477	513
Loans charged-off	(267)	(625)	(292)	(1,223)
Allowance for loan losses, ending	7,489	7,594	7,489	7,594
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	5,059	3,139	3,983	3,241
Provision charged to operating expenses	801	1,609	2,100	1,749
Recoveries of loans previously charged-off	0	55	0	85
Loans charged-off	(109)	(1,580)	(332)	(1,852)
Allowance for loan losses, ending	5,751	3,223	5,751	3,223
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	863	438	324	435
Provision charged to operating expenses	45	101	711	168
Recoveries of loans previously charged-off	7	3	10	4
Loans charged-off	(36)	(198)	(166)	(263)
Allowance for loan losses, ending	879	344	879	344
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	1,258	797	793	831
Provision charged to operating expenses	562	301	1,329	381
Recoveries of loans previously charged-off	11	20	69	65
Loans charged-off	(515)	(329)	(875)	(488)
Allowance for loan losses, ending	1,316	789	1,316	789
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	218	101	789	65
Provision charged to operating expenses	257	553	(314)	589
Recoveries of loans previously charged-off	0	0	0	0
Loans charged-off	0	0	0	0
Allowance for loan losses, ending	$ 475	$ 654	$ 475	$ 654