Investment Securities (Schedule Of Unrealized Loss On Investments) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 170,365	$ 1,990,616
Less than 12 Months, Unrealized Losses	352	14,491
12 Months or Longer, Fair Value	42,459	585,640
12 Months or Longer, Unrealized Losses	640	12,792
Total Fair Value, Fair Value	212,824	2,576,256
Total Fair Value, Unrealized Losses	992	27,283
Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	122,626
Less than 12 Months, Unrealized Losses	0	639
12 Months or Longer, Fair Value	9,785	18,435
12 Months or Longer, Unrealized Losses	81	482
Total Fair Value, Fair Value	9,785	141,061
Total Fair Value, Unrealized Losses	81	1,121
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	170,365	1,656,194
Less than 12 Months, Unrealized Losses	352	12,874
12 Months or Longer, Fair Value	0	489,971
12 Months or Longer, Unrealized Losses	0	9,688
Total Fair Value, Fair Value	170,365	2,146,165
Total Fair Value, Unrealized Losses	352	22,562
Collateralized Mortgage Obligations Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	196,811
Less than 12 Months, Unrealized Losses	0	963
12 Months or Longer, Fair Value	27,827	72,366
12 Months or Longer, Unrealized Losses	142	2,262
Total Fair Value, Fair Value	27,827	269,177
Total Fair Value, Unrealized Losses	142	3,225
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	53	50
12 Months or Longer, Unrealized Losses	1	1
Total Fair Value, Fair Value	53	50
Total Fair Value, Unrealized Losses	1	1
Other Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	14,985
Less than 12 Months, Unrealized Losses	0	15
12 Months or Longer, Fair Value	4,794	4,818
12 Months or Longer, Unrealized Losses	416	359
Total Fair Value, Fair Value	4,794	19,803
Total Fair Value, Unrealized Losses	$ 416	$ 374