Securities (Schedule of Securities Available-for-Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 714,056	$ 631,800
Gross Unrealized Gains	19,432	10,400
Gross Unrealized Losses	(577)	(4,360)
Total Fair Value	732,911	637,840
U.S. Treasury and Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	0	10,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(102)
Total Fair Value	0	9,898
Obligations of State and Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	234,656	195,360
Gross Unrealized Gains	12,630	8,286
Gross Unrealized Losses	(76)	(18)
Total Fair Value	247,210	203,628
Mortgage-backed Securities - Residential
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	479,047	426,087
Gross Unrealized Gains	6,802	2,114
Gross Unrealized Losses	(501)	(4,240)
Total Fair Value	485,348	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