Loans Receivable and Allowance for Loan Losses (Summary of Allowances on Loans Receivable, by Class) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	$ 25,871	$ 24,271	$ 24,998	$ 23,110
Provision charged to operating expenses	2,250	2,100	6,350	4,100
Recoveries of loans previously charged-off	99	255	257	2,234
Loans charged-off	(1,478)	(2,086)	(4,863)	(4,904)
Allowance for loan losses, ending	26,742	24,540	26,742	24,540
Commercial and industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	12,038	7,100	11,714	8,178
Provision charged to operating expenses	946	3,047	3,088	1,575
Recoveries of loans previously charged-off	53	137	160	1,386
Loans charged-off	(1,321)	(300)	(3,246)	(1,155)
Allowance for loan losses, ending	11,716	9,984	11,716	9,984
Commercial tax-exempt [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	45	67	55	72
Provision charged to operating expenses	1	0	(9)	(5)
Recoveries of loans previously charged-off	0	0	0	0
Loans charged-off	0	0	0	0
Allowance for loan losses, ending	46	67	46	67
Owner occupied real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	1,934	2,233	1,931	2,180
Provision charged to operating expenses	1,079	(98)	1,197	(135)
Recoveries of loans previously charged-off	0	24	3	310
Loans charged-off	0	(187)	(118)	(383)
Allowance for loan losses, ending	3,013	1,972	3,013	1,972
Commercial construction and land development [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	4,476	6,696	4,242	5,559
Provision charged to operating expenses	(6)	(1,954)	226	(489)
Recoveries of loans previously charged-off	0	34	2	245
Loans charged-off	0	(754)	0	(1,293)
Allowance for loan losses, ending	4,470	4,022	4,470	4,022
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	5,178	4,840	4,707	4,161
Provision charged to operating expenses	67	260	1,216	1,481
Recoveries of loans previously charged-off	12	2	29	176
Loans charged-off	(16)	(355)	(711)	(1,071)
Allowance for loan losses, ending	5,241	4,747	5,241	4,747
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	855	1,061	796	960
Provision charged to operating expenses	(31)	581	109	964
Recoveries of loans previously charged-off	17	0	19	20
Loans charged-off	(23)	(38)	(106)	(340)
Allowance for loan losses, ending	818	1,604	818	1,604
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	959	1,333	931	1,303
Provision charged to operating expenses	(6)	427	559	628
Recoveries of loans previously charged-off	17	58	44	97
Loans charged-off	(118)	(452)	(682)	(662)
Allowance for loan losses, ending	852	1,366	852	1,366
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	386	941	622	697
Provision charged to operating expenses	200	(163)	(36)	81
Recoveries of loans previously charged-off	0	0	0	0
Loans charged-off	0	0	0	0
Allowance for loan losses, ending	$ 586	$ 778	$ 586	$ 778