Investment Securities (Summary of Amortized Cost and Fair Value of Held-to-Maturity Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	$ 273,905	$ 229,977
Investment securities held-to-maturity, Unrealized Gains	5,462	8,087
Held-to-maturity Securities, Unrecognized Holding Loss	11,096	8,142
Held-to-maturity Securities, Fair Value	268,271	229,922
State and political subdivisions [Member]
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	263,405	219,477
Investment securities held-to-maturity, Unrealized Gains	5,462	8,087
Held-to-maturity Securities, Unrecognized Holding Loss	6,846	3,367
Held-to-maturity Securities, Fair Value	262,021	224,197
Trust preferred securities [Member]
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	10,500	10,500
Investment securities held-to-maturity, Unrealized Gains	0	0
Held-to-maturity Securities, Unrecognized Holding Loss	4,250	4,775
Held-to-maturity Securities, Fair Value	$ 6,250	$ 5,725