Investment Securities Available for Sale (Schedule Of Unrealized Loss On Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 1,990,616	$ 271,472
Less than 12 Months, Unrealized Losses	14,491	824
12 Months or Longer, Fair Value	585,640	942,667
12 Months or Longer, Unrealized Losses	12,792	11,531
Total Fair Value	2,576,256	1,214,139
Total Unrealized Losses	27,283	12,355
Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	122,626	0
Less than 12 Months, Unrealized Losses	639	0
12 Months or Longer, Fair Value	18,435	21,488
12 Months or Longer, Unrealized Losses	482	440
Total Fair Value	141,061	21,488
Total Unrealized Losses	1,121	440
Mortgage-Backed Securities Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	1,656,194	251,134
Less than 12 Months, Unrealized Losses	12,874	763
12 Months or Longer, Fair Value	489,971	798,282
12 Months or Longer, Unrealized Losses	9,688	8,368
Total Fair Value	2,146,165	1,049,416
Total Unrealized Losses	22,562	9,131
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	196,811	20,338
Less than 12 Months, Unrealized Losses	963	61
12 Months or Longer, Fair Value	72,366	119,172
12 Months or Longer, Unrealized Losses	2,262	2,281
Total Fair Value	269,177	139,510
Total Unrealized Losses	3,225	2,342
State And Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	0
Less than 12 Months, Unrealized Losses	0	0
12 Months or Longer, Fair Value	50	45
12 Months or Longer, Unrealized Losses	1	1
Total Fair Value	50	45
Total Unrealized Losses	1	1
Other Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	14,985	0
Less than 12 Months, Unrealized Losses	15	0
12 Months or Longer, Fair Value	4,818	3,680
12 Months or Longer, Unrealized Losses	359	441
Total Fair Value	19,803	3,680
Total Unrealized Losses	$ 374	$ 441