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
	Mar. 31, 2014	Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	$ 23,110	$ 25,282
Provision charged to operating expenses	900	2,300
Recoveries of loans previously charged-off	1,444	666
Loans charged-off	(1,520)	(776)
Allowance for loan losses, ending	23,934	27,472
Commercial and industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	8,178	9,959
Provision charged to operating expenses	(915)	347
Recoveries of loans previously charged-off	1,005	138
Loans charged-off	(354)	(36)
Allowance for loan losses, ending	7,914	10,408
Commercial tax-exempt [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	72	83
Provision charged to operating expenses	(4)	(8)
Recoveries of loans previously charged-off	0	0
Loans charged-off	0	0
Allowance for loan losses, ending	68	75
Owner occupied real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	2,180	2,129
Provision charged to operating expenses	(162)	260
Recoveries of loans previously charged-off	243	3
Loans charged-off	(25)	(184)
Allowance for loan losses, ending	2,236	2,208
Commercial construction and land development [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	5,559	7,222
Provision charged to operating expenses	195	276
Recoveries of loans previously charged-off	100	486
Loans charged-off	(12)	(17)
Allowance for loan losses, ending	5,842	7,967
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	4,161	3,983
Provision charged to operating expenses	1,122	1,137
Recoveries of loans previously charged-off	73	0
Loans charged-off	(716)	(82)
Allowance for loan losses, ending	4,640	5,038
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	960	324
Provision charged to operating expenses	346	127
Recoveries of loans previously charged-off	0	3
Loans charged-off	(283)	(116)
Allowance for loan losses, ending	1,023	338
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	1,303	793
Provision charged to operating expenses	133	299
Recoveries of loans previously charged-off	23	36
Loans charged-off	(130)	(341)
Allowance for loan losses, ending	1,329	787
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning	697	789
Provision charged to operating expenses	185	(138)
Recoveries of loans previously charged-off	0	0
Loans charged-off	0	0
Allowance for loan losses, ending	$ 882	$ 651