Available-For-Sale And Held-To-Maturity Securities (Schedule Of Gross Unrealized Losses And The Estimated Fair Value By Length Of Time In A Loss Position) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($)
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	$ (15,812)
Available-for-sale Securities, Estimated fair value, Less than 12 months	1,146,246
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(4,956)
Available-for-sale Securities, Estimated fair value, 12 months or more	130,815
Available-for-sale Securities, Gross unrealized losses, Total	(20,768)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	1,277,061
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(7,280)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	446,111
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(2,087)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	107,364
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total	(9,367)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value, Total	553,475
U.S. Government Agency Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(2)
Available-for-sale Securities, Estimated fair value, Less than 12 months	578
Available-for-sale Securities, Gross unrealized losses, Total	(2)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	578
State And Municipal Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(128)
Available-for-sale Securities, Estimated fair value, Less than 12 months	13,784
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(1,598)
Available-for-sale Securities, Estimated fair value, 12 months or more	56,128
Available-for-sale Securities, Gross unrealized losses, Total	(1,726)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	69,912
Corporate Fixed Income Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(45)
Available-for-sale Securities, Estimated fair value, Less than 12 months	15,848
Available-for-sale Securities, Gross unrealized losses, Total	(45)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	15,848
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(40)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	35,064
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total	(40)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value, Total	35,064
Asset-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(8,488)
Available-for-sale Securities, Estimated fair value, Less than 12 months	729,217
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(3,013)
Available-for-sale Securities, Estimated fair value, 12 months or more	63,917
Available-for-sale Securities, Gross unrealized losses, Total	(11,501)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	793,134
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(2,791)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	316,535
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(2,014)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	69,521
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total	(4,805)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value, Total	386,056
Mortgage Backed Securities [Member] | Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(7,060)
Available-for-sale Securities, Estimated fair value, Less than 12 months	374,478
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(167)
Available-for-sale Securities, Estimated fair value, 12 months or more	8,510
Available-for-sale Securities, Gross unrealized losses, Total	(7,227)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	382,988
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(4,489)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	129,576
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(15)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2,002
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total	(4,504)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value, Total	131,578
Mortgage Backed Securities [Member] | Commercial [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than 12 months	(89)
Available-for-sale Securities, Estimated fair value, Less than 12 months	12,341
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(1)
Available-for-sale Securities, Estimated fair value, 12 months or more	111
Available-for-sale Securities, Gross unrealized losses, Total	(90)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	12,452
Mortgage Backed Securities [Member] | Non-Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, 12 months or more	(177)
Available-for-sale Securities, Estimated fair value, 12 months or more	2,149
Available-for-sale Securities, Gross unrealized losses, Total	(177)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value, Total	2,149
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(18)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	777
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss, Total	(18)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value, Total	$ 777