Investment Securities (Schedule Of Unrealized Loss On Investments) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 559,661	$ 1,990,616
Less than 12 Months, Unrealized Losses	1,602	14,491
12 Months or Longer, Fair Value	117,916	585,640
12 Months or Longer, Unrealized Losses	1,128	12,792
Total Fair Value, Fair Value	677,577	2,576,256
Total Fair Value, Unrealized Losses	2,730	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	11,938	18,435
12 Months or Longer, Unrealized Losses	143	482
Total Fair Value, Fair Value	11,938	141,061
Total Fair Value, Unrealized Losses	143	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	559,661	1,656,194
Less than 12 Months, Unrealized Losses	1,602	12,874
12 Months or Longer, Fair Value	29,281	489,971
12 Months or Longer, Unrealized Losses	169	9,688
Total Fair Value, Fair Value	588,942	2,146,165
Total Fair Value, Unrealized Losses	1,771	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	71,875	72,366
12 Months or Longer, Unrealized Losses	393	2,262
Total Fair Value, Fair Value	71,875	269,177
Total Fair Value, Unrealized Losses	393	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	51	50
12 Months or Longer, Unrealized Losses	1	1
Total Fair Value, Fair Value	51	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	4,771	4,818
12 Months or Longer, Unrealized Losses	422	359
Total Fair Value, Fair Value	4,771	19,803
Total Fair Value, Unrealized Losses	$ 422	$ 374