Investment Securities AFS Gross Unrealized Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Sep. 30, 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	$ (91,755)	$ (4,832)
Unrealized losses on available for sale securities, 12 months or more	(5,735)	(88)
Total unrealized losses on available for sale securities	(97,490)	(4,920)
Fair value of unrealized losses on available for sale securities, less than 12 months	2,227,291	1,000,503
Fair value of unrealized losses on available for sale securities, 12 months or more	90,035	509
Total fair value of unrealized losses on available for sale securities	2,317,326	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	(1,139)	(42)
Unrealized losses on available for sale securities, 12 months or more	(11)	(13)
Total unrealized losses on available for sale securities	(1,150)	(55)
Fair value of unrealized losses on available for sale securities, less than 12 months	41,004	5,065
Fair value of unrealized losses on available for sale securities, 12 months or more	348	348
Total fair value of unrealized losses on available for sale securities	41,352	5,413
Number of available for sale securities in a continuous unrealized loss position less than twelve months	104	15
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	1	1
Government-Sponsored Enterprise (GSE) [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	(73,511)	(3,727)
Unrealized losses on available for sale securities, 12 months or more	(5,684)	0
Total unrealized losses on available for sale securities	(79,195)	(3,727)
Fair value of unrealized losses on available for sale securities, less than 12 months	1,769,200	892,964
Fair value of unrealized losses on available for sale securities, 12 months or more	89,503	0
Total fair value of unrealized losses on available for sale securities	1,858,703	892,964
Number of available for sale securities in a continuous unrealized loss position less than twelve months	88	30
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	3	0
Private Label [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	(36)	0
Unrealized losses on available for sale securities, 12 months or more	0	0
Total unrealized losses on available for sale securities	(36)	0
Fair value of unrealized losses on available for sale securities, less than 12 months	2,129	0
Fair value of unrealized losses on available for sale securities, 12 months or more	38	50
Total fair value of unrealized losses on available for sale securities	2,167	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
Commercial Mortgage 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	(17,037)	(1,063)
Unrealized losses on available for sale securities, 12 months or more	0	0
Total unrealized losses on available for sale securities	(17,037)	(1,063)
Fair value of unrealized losses on available for sale securities, less than 12 months	408,495	102,474
Fair value of unrealized losses on available for sale securities, 12 months or more	0	0
Total fair value of unrealized losses on available for sale securities	408,495	102,474
Number of available for sale securities in a continuous unrealized loss position less than twelve months	15	2
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	0	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	(32)	0
Unrealized losses on available for sale securities, 12 months or more	(40)	(75)
Total unrealized losses on available for sale securities	(72)	(75)
Fair value of unrealized losses on available for sale securities, less than 12 months	6,463	0
Fair value of unrealized losses on available for sale securities, 12 months or more	146	111
Total fair value of unrealized losses on available for sale securities	$ 6,609	$ 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	1	1