Securities (Schedule of Securities Available-for-Sale) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 703,362	$ 631,800
Gross Unrealized Gains	13,909	10,400
Gross Unrealized Losses	(1,660)	(4,360)
Total Fair Value	715,611	637,840
U.S. Treasury and Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,001	10,000
Gross Unrealized Gains	8	0
Gross Unrealized Losses	0	(102)
Total Fair Value	11,009	9,898
Obligations of State and Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	227,294	195,360
Gross Unrealized Gains	9,295	8,286
Gross Unrealized Losses	(306)	(18)
Total Fair Value	236,283	203,628
Mortgage-backed Securities - Residential
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	464,714	426,087
Gross Unrealized Gains	4,606	2,114
Gross Unrealized Losses	(1,354)	(4,240)
Total Fair Value	467,966	423,961
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