Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	$ 38,413	$ 18,352
Less than 12 Months Fair Value	234,538	918,813
Less than 12 Months Unrealized Losses	(1,025)	(9,247)
12 Months or More Fair Value	170,158	298,316
12 Months or More Unrealized Losses	(2,025)	(9,021)
Total Fair Value	404,696	1,217,129
Total Unrealized Losses	(3,050)	(18,268)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	3,050	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	17,148	4,525
Less than 12 Months Fair Value	176,508	664,509
Less than 12 Months Unrealized Losses	(548)	(7,610)
12 Months or More Fair Value	163,859	214,325
12 Months or More Unrealized Losses	(1,834)	(7,381)
Total Fair Value	340,367	878,834
Total Unrealized Losses	(2,382)	(14,991)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2,382	14,991
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities Gross Unrealized Gain, instant	16,192	12,690
Less than 12 Months Fair Value	35,915	48,261
Less than 12 Months Unrealized Losses	(337)	(358)
12 Months or More Fair Value	3,489	31,383
12 Months or More Unrealized Losses	(45)	(580)
Total Fair Value	39,404	79,644
Total Unrealized Losses	(382)	(938)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	382	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	5,009	1,113
Less than 12 Months Fair Value	22,115	193,400
Less than 12 Months Unrealized Losses	(140)	(1,128)
12 Months or More Fair Value	0	40,034
12 Months or More Unrealized Losses	0	(718)
Total Fair Value	22,115	233,434
Total Unrealized Losses	(140)	(1,846)
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	140	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	64	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