Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	$ 33,588	$ 18,352
Less than 12 Months Fair Value	125,078	918,813
Less than 12 Months Unrealized Losses	(658)	(9,247)
12 Months or More Fair Value	213,295	298,316
12 Months or More Unrealized Losses	(3,763)	(9,021)
Total Fair Value	338,373	1,217,129
Total Unrealized Losses	(4,421)	(18,268)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	4,421	18,268
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	14,247	4,525
Less than 12 Months Fair Value	95,313	664,509
Less than 12 Months Unrealized Losses	(533)	(7,610)
12 Months or More Fair Value	190,975	214,325
12 Months or More Unrealized Losses	(3,328)	(7,381)
Total Fair Value	286,288	878,834
Total Unrealized Losses	(3,861)	(14,991)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	3,861	14,991
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	14,257	12,690
Less than 12 Months Fair Value	25,702	48,261
Less than 12 Months Unrealized Losses	(125)	(358)
12 Months or More Fair Value	19,010	31,383
12 Months or More Unrealized Losses	(289)	(580)
Total Fair Value	44,712	79,644
Total Unrealized Losses	(414)	(938)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	414	938
US Government Corporations and Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	5,031	1,113
Less than 12 Months Fair Value	4,063	193,400
Less than 12 Months Unrealized Losses	0	(1,128)
12 Months or More Fair Value	500	40,034
12 Months or More Unrealized Losses	0	(718)
Total Fair Value	4,563	233,434
Total Unrealized Losses	0	(1,846)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	1,846
US Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	0	0
Less than 12 Months Fair Value		10,343
Less than 12 Months Unrealized Losses		(136)
12 Months or More Fair Value		9,794
12 Months or More Unrealized Losses		(166)
Total Fair Value		20,137
Total Unrealized Losses		(302)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	302
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	53	24
Less than 12 Months Fair Value	0	2,300
Less than 12 Months Unrealized Losses	0	(15)
12 Months or More Fair Value	2,810	2,780
12 Months or More Unrealized Losses	(146)	(176)
Total Fair Value	2,810	5,080
Total Unrealized Losses	(146)	(191)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 146	$ 191