Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investment [Line Items]
Less than 12 months, Fair Value	$ 2,125,723	$ 3,012,123
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5,488	75,636
12 months or longer, Fair Value	1,137,135	421,202
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	29,896	42,542
Total, Fair Value	3,262,858	3,433,325
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	35,384	118,178
US Treasury and Government [Member]
Investment [Line Items]
Less than 12 months, Fair Value	90,261	96,172
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	818	243
12 months or longer, Fair Value	32,077	59,677
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	4,206	12,901
Total, Fair Value	122,338	155,849
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	5,024	13,144
Government-sponsored enterprise obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	224,808	487,317
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	922	18,155
12 months or longer, Fair Value	224,779	93,654
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	7,118	9,126
Total, Fair Value	449,587	580,971
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	8,040	27,281
State and municipal obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	172,980	478,818
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	646	15,520
12 months or longer, Fair Value	215,702	178,150
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	7,708	17,825
Total, Fair Value	388,682	656,968
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	8,354	33,345
Agency mortgage-backed securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	55,128	717,778
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	429	26,124
12 months or longer, Fair Value	381,617	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,163	0
Total, Fair Value	436,745	717,778
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	5,592	26,124
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	141,655	53,454
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	609	918
12 months or longer, Fair Value	43,659	22,289
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	619	702
Total, Fair Value	185,314	75,743
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	1,228	1,620
Other asset-backed securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	1,424,457	1,088,556
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,009	9,072
12 months or longer, Fair Value	159,098	58,398
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,094	1,097
Total, Fair Value	1,583,555	1,146,954
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	5,103	10,169
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	1,621,240	1,859,788
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3,047	36,114
12 months or longer, Fair Value	584,374	80,687
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	8,876	1,799
Total, Fair Value	2,205,614	1,940,475
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	11,923	37,913
Other debt securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	16,434	90,028
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	55	5,604
12 months or longer, Fair Value	80,203	9,034
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,988	891
Total, Fair Value	96,637	99,062
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 2,043	$ 6,495