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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	$ 24,271	$ 28,038	$ 23,110	$ 25,282
Provision charged to operating expenses	2,100	1,200	4,100	5,300
Recoveries of loans previously charged-off	255	610	2,234	1,504
Loans charged-off	(2,086)	(2,423)	(4,904)	(4,661)
Allowance for loan losses, ending	24,540	27,425	24,540	27,425
Commercial and industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	7,100	10,549	8,178	9,959
Provision charged to operating expenses	3,047	(437)	1,575	1,085
Recoveries of loans previously charged-off	137	613	1,386	945
Loans charged-off	(300)	(1,462)	(1,155)	(2,726)
Allowance for loan losses, ending	9,984	9,263	9,984	9,263
Commercial tax-exempt [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	67	74	72	83
Provision charged to operating expenses	0	1	(5)	(8)
Recoveries of loans previously charged-off	0	0	0	0
Loans charged-off	0	0	0	0
Allowance for loan losses, ending	67	75	67	75
Owner occupied real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	2,233	2,207	2,180	2,129
Provision charged to operating expenses	(98)	4	(135)	315
Recoveries of loans previously charged-off	24	0	310	3
Loans charged-off	(187)	(34)	(383)	(270)
Allowance for loan losses, ending	1,972	2,177	1,972	2,177
Commercial construction and land development [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	6,696	7,810	5,559	7,222
Provision charged to operating expenses	(1,954)	(33)	(489)	82
Recoveries of loans previously charged-off	34	(21)	245	477
Loans charged-off	(754)	(267)	(1,293)	(292)
Allowance for loan losses, ending	4,022	7,489	4,022	7,489
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	4,840	5,059	4,161	3,983
Provision charged to operating expenses	260	801	1,481	2,100
Recoveries of loans previously charged-off	2	0	176	0
Loans charged-off	(355)	(109)	(1,071)	(332)
Allowance for loan losses, ending	4,747	5,751	4,747	5,751
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	1,061	863	960	324
Provision charged to operating expenses	581	45	964	711
Recoveries of loans previously charged-off	0	7	20	10
Loans charged-off	(38)	(36)	(340)	(166)
Allowance for loan losses, ending	1,604	879	1,604	879
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	1,333	1,258	1,303	793
Provision charged to operating expenses	427	562	628	1,329
Recoveries of loans previously charged-off	58	11	97	69
Loans charged-off	(452)	(515)	(662)	(875)
Allowance for loan losses, ending	1,366	1,316	1,366	1,316
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	941	218	697	789
Provision charged to operating expenses	(163)	257	81	(314)
Recoveries of loans previously charged-off	0	0	0	0
Loans charged-off	0	0	0	0
Allowance for loan losses, ending	$ 778	$ 475	$ 778	$ 475