Securities (Amortized Cost, Unrealized Gross Gains and Losses Recognized in Accumulated Other Comprehensive Income (Loss), and Fair Value of Securities Available-for-Sale) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 609,561	$ 626,383
Gross Unrealized Gains	12,561	10,130
Gross Unrealized Losses	(2,544)	(5,518)
Securities Available-for-Sale, at Fair Value	619,578	630,995
U.S. Treasury and Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,000	20,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(80)	(439)
Securities Available-for-Sale, at Fair Value	19,920	19,561
Obligations of State and Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	151,288	147,321
Gross Unrealized Gains	7,546	6,515
Gross Unrealized Losses	(34)	(59)
Securities Available-for-Sale, at Fair Value	158,800	153,777
Mortgage-backed Securities - Residential
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	437,920	458,709
Gross Unrealized Gains	5,015	3,615
Gross Unrealized Losses	(2,430)	(5,020)
Securities Available-for-Sale, at Fair Value	440,505	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
Securities Available-for-Sale, at Fair Value	$ 353	$ 353