Investment Securities AFS Gross Unrealized Losses (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	$ (82,852)	$ (4,832)
Unrealized losses on available for sale securities, 12 months or more	(25,182)	(88)
Total unrealized losses on available for sale securities	(108,034)	(4,920)
Fair value of unrealized losses on available for sale securities, less than 12 months	2,386,847	1,000,503
Fair value of unrealized losses on available for sale securities, 12 months or more	467,340	509
Total fair value of unrealized losses on available for sale securities	2,854,187	1,001,012
Obligations of state and political subdivisions (municipal securities) [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	(1,525)	(42)
Unrealized losses on available for sale securities, 12 months or more	(8)	(13)
Total unrealized losses on available for sale securities	(1,533)	(55)
Fair value of unrealized losses on available for sale securities, less than 12 months	47,044	5,065
Fair value of unrealized losses on available for sale securities, 12 months or more	273	348
Total fair value of unrealized losses on available for sale securities	47,317	5,413
Number of available for sale securities in a continuous unrealized loss position less than twelve months	113	15
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	1	1
Government-Sponsored Enterprise (GSE) Residential Mortgages [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	(57,393)	(3,727)
Unrealized losses on available for sale securities, 12 months or more	(21,186)	0
Total unrealized losses on available for sale securities	(78,579)	(3,727)
Fair value of unrealized losses on available for sale securities, less than 12 months	1,887,784	892,964
Fair value of unrealized losses on available for sale securities, 12 months or more	421,082	0
Total fair value of unrealized losses on available for sale securities	2,308,866	892,964
Number of available for sale securities in a continuous unrealized loss position less than twelve months	106,000	30
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	15,000	0
Private Label Residential Mortgages [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	(37)	0
Unrealized losses on available for sale securities, 12 months or more	0	0
Total unrealized losses on available for sale securities	(37)	0
Fair value of unrealized losses on available for sale securities, less than 12 months	2,105	0
Fair value of unrealized losses on available for sale securities, 12 months or more	35	50
Total fair value of unrealized losses on available for sale securities	2,140	50
Number of available for sale securities in a continuous unrealized loss position less than twelve months	2	0
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	1	1
GSE Commercial Mortgage-Related Securities [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	(23,854)	(1,063)
Unrealized losses on available for sale securities, 12 months or more	(3,988)	0
Total unrealized losses on available for sale securities	(27,842)	(1,063)
Fair value of unrealized losses on available for sale securities, less than 12 months	443,462	102,474
Fair value of unrealized losses on available for sale securities, 12 months or more	45,950	0
Total fair value of unrealized losses on available for sale securities	489,412	102,474
Number of available for sale securities in a continuous unrealized loss position less than twelve months	19	2
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	1	0
Asset-backed Securities [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months		0
Unrealized losses on available for sale securities, 12 months or more		0
Total unrealized losses on available for sale securities		0
Fair value of unrealized losses on available for sale securities, less than 12 months		0
Fair value of unrealized losses on available for sale securities, 12 months or more		0
Total fair value of unrealized losses on available for sale securities		0
Number of available for sale securities in a continuous unrealized loss position less than twelve months		0
Number of available for sale securities in a continuous unrealized loss position for twelve months or more		0
Other Debt And Other Equity Securities [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	(43)	0
Unrealized losses on available for sale securities, 12 months or more	0	(75)
Total unrealized losses on available for sale securities	(43)	(75)
Fair value of unrealized losses on available for sale securities, less than 12 months	6,452	0
Fair value of unrealized losses on available for sale securities, 12 months or more	0	111
Total fair value of unrealized losses on available for sale securities	$ 6,452	$ 111
Number of available for sale securities in a continuous unrealized loss position less than twelve months	5	0
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	0	1