Securities (Schedule of Securities Available-for-Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 617,925	$ 626,383
Gross Unrealized Gains	9,976	10,130
Gross Unrealized Losses	(2,757)	(5,518)
Total Fair Value	625,144	630,995
U.S. Treasury and Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,000	20,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(30)	(439)
Total Fair Value	9,970	19,561
Obligations of State and Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	187,819	147,321
Gross Unrealized Gains	5,885	6,515
Gross Unrealized Losses	(362)	(59)
Total Fair Value	193,342	153,777
Mortgage-backed Securities - Residential
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	419,753	458,709
Gross Unrealized Gains	4,091	3,615
Gross Unrealized Losses	(2,365)	(5,020)
Total Fair Value	421,479	457,304
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	353	353
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total Fair Value	$ 353	$ 353