Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	$ 22,541	$ 22,551
Less than 12 Months Fair Value	242,579	887,693
Less than 12 Months Unrealized Losses	(1,590)	(23,148)
12 Months or More Fair Value	591,058	166,348
12 Months or More Unrealized Losses	(19,324)	(15,783)
Total Fair Value	833,637	1,054,041
Total Unrealized Losses	(20,914)	(38,931)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	20,914	38,931
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	7,950	10,640
Less than 12 Months Fair Value	162,583	492,921
Less than 12 Months Unrealized Losses	(1,219)	(10,991)
12 Months or More Fair Value	283,292	121,303
12 Months or More Unrealized Losses	(11,848)	(12,684)
Total Fair Value	445,875	614,224
Total Unrealized Losses	(13,067)	(23,675)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	13,067	23,674
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	14,101	11,450
Less than 12 Months Fair Value	29,307	112,400
Less than 12 Months Unrealized Losses	(170)	(3,069)
12 Months or More Fair Value	52,322	13,815
12 Months or More Unrealized Losses	(1,296)	(923)
Total Fair Value	81,629	126,215
Total Unrealized Losses	(1,466)	(3,992)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,466	3,993
US Government Corporations and Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	467	434
Less than 12 Months Fair Value	50,689	260,001
Less than 12 Months Unrealized Losses	(201)	(8,063)
12 Months or More Fair Value	231,082	28,447
12 Months or More Unrealized Losses	(5,419)	(2,003)
Total Fair Value	281,771	288,448
Total Unrealized Losses	(5,620)	(10,066)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5,620	10,066
US Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	1	0
Less than 12 Months Fair Value	0	20,114
Less than 12 Months Unrealized Losses	0	(967)
12 Months or More Fair Value	19,253	0
12 Months or More Unrealized Losses	(600)	0
Total Fair Value	19,253	20,114
Total Unrealized Losses	(600)	(967)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	600	967
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	22	27
Less than 12 Months Fair Value	0	2,257
Less than 12 Months Unrealized Losses	0	(58)
12 Months or More Fair Value	5,109	2,783
12 Months or More Unrealized Losses	(161)	(173)
Total Fair Value	5,109	5,040
Total Unrealized Losses	(161)	(231)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 161	$ 231