Securities (Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,581,989	$ 1,680,491
Available-for-sale Securities, Gross Unrealized Gain, instant	26,156	22,551
Gross Unrealized Losses	18,128	38,931
Fair Value	1,590,017	1,664,111
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	862,248	961,442
Available-for-sale Securities, Gross Unrealized Gain, instant	11,858	10,640
Gross Unrealized Losses	11,488	23,674
Fair Value	862,618	948,408
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	368,221	357,013
Available-for-sale Securities, Gross Unrealized Gain, instant	13,783	11,450
Gross Unrealized Losses	1,498	3,993
Fair Value	380,506	364,470
U.S. Government and Government-Sponsored Enterprise Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	325,341	335,671
Available-for-sale Securities, Gross Unrealized Gain, instant	492	434
Gross Unrealized Losses	4,444	10,066
Fair Value	321,389	326,039
US Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,895	21,081
Available-for-sale Securities, Gross Unrealized Gain, instant	1	0
Gross Unrealized Losses	559	967
Fair Value	20,337	20,114
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,284	5,284
Available-for-sale Securities, Gross Unrealized Gain, instant	22	27
Gross Unrealized Losses	139	231
Fair Value	$ 5,167	$ 5,080