Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	$ 29,138	$ 25,527
Less than 12 Months Fair Value	162,400	437,414
Less than 12 Months Unrealized Losses	(966)	(2,350)
12 Months or More Fair Value	301,749	561,668
12 Months or More Unrealized Losses	(5,476)	(11,989)
Total Fair Value	464,149	999,082
Total Unrealized Losses	(6,442)	(14,339)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	6,442	14,339
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	12,610	10,219
Less than 12 Months Fair Value	124,092	258,825
Less than 12 Months Unrealized Losses	(804)	(1,287)
12 Months or More Fair Value	204,165	279,015
12 Months or More Unrealized Losses	(4,328)	(6,924)
Total Fair Value	328,257	537,840
Total Unrealized Losses	(5,132)	(8,211)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5,132	8,210
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	13,574	14,432
Less than 12 Months Fair Value	37,808	71,026
Less than 12 Months Unrealized Losses	(161)	(543)
12 Months or More Fair Value	29,960	44,148
12 Months or More Unrealized Losses	(594)	(982)
Total Fair Value	67,768	115,174
Total Unrealized Losses	(755)	(1,525)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	755	1,526
US Government Corporations and Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	2,922	856
Less than 12 Months Fair Value	500	105,250
Less than 12 Months Unrealized Losses	(1)	(518)
12 Months or More Fair Value	54,892	216,221
12 Months or More Unrealized Losses	(374)	(3,551)
Total Fair Value	55,392	321,471
Total Unrealized Losses	(375)	(4,069)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	375	4,069
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	0
Less than 12 Months Unrealized Losses	0	0
12 Months or More Fair Value	9,925	19,450
12 Months or More Unrealized Losses	(32)	(411)
Total Fair Value	9,925	19,450
Total Unrealized Losses	(32)	(411)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	32	411
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	31	20
Less than 12 Months Fair Value	0	2,313
Less than 12 Months Unrealized Losses	0	(2)
12 Months or More Fair Value	2,807	2,834
12 Months or More Unrealized Losses	(148)	(121)
Total Fair Value	2,807	5,147
Total Unrealized Losses	(148)	(123)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 148	$ 123