Investment Securities AFS Gross Unrealized Losses (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
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	$ (3,404)	$ (82,852)
Unrealized losses on available for sale securities, 12 months or more	(68,091)	(25,182)
Total unrealized losses on available for sale securities	(71,495)	(108,034)
Fair value of unrealized losses on available for sale securities, less than 12 months	699,084	2,386,847
Fair value of unrealized losses on available for sale securities, 12 months or more	1,786,065	467,340
Total fair value of unrealized losses on available for sale securities	2,485,149	2,854,187
US Treasury 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	(3)
Unrealized losses on available for sale securities, 12 months or more	0
Total unrealized losses on available for sale securities	(3)
Fair value of unrealized losses on available for sale securities, less than 12 months	996
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	996
Number of available for sale securities in a continuous unrealized loss position less than twelve months	1
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	0
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)	(1,525)
Unrealized losses on available for sale securities, 12 months or more	(47)	(8)
Total unrealized losses on available for sale securities	(48)	(1,533)
Fair value of unrealized losses on available for sale securities, less than 12 months	1,799	47,044
Fair value of unrealized losses on available for sale securities, 12 months or more	5,647	273
Total fair value of unrealized losses on available for sale securities	7,446	47,317
Number of available for sale securities in a continuous unrealized loss position less than twelve months	5	113
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	13	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	(1,472)	(57,393)
Unrealized losses on available for sale securities, 12 months or more	(41,753)	(21,186)
Total unrealized losses on available for sale securities	(43,225)	(78,579)
Fair value of unrealized losses on available for sale securities, less than 12 months	331,085	1,887,784
Fair value of unrealized losses on available for sale securities, 12 months or more	1,389,945	421,082
Total fair value of unrealized losses on available for sale securities	1,721,030	2,308,866
Number of available for sale securities in a continuous unrealized loss position less than twelve months	30	106
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	64	15
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	(1)	(37)
Unrealized losses on available for sale securities, 12 months or more	(1)	0
Total unrealized losses on available for sale securities	(2)	(37)
Fair value of unrealized losses on available for sale securities, less than 12 months	1,889	2,105
Fair value of unrealized losses on available for sale securities, 12 months or more	30	35
Total fair value of unrealized losses on available for sale securities	1,919	2,140
Number of available for sale securities in a continuous unrealized loss position less than twelve months	1	2
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	2	1
GNMA 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	(1,927)	(23,854)
Unrealized losses on available for sale securities, 12 months or more	(26,290)	(3,988)
Total unrealized losses on available for sale securities	(28,217)	(27,842)
Fair value of unrealized losses on available for sale securities, less than 12 months	363,315	443,462
Fair value of unrealized losses on available for sale securities, 12 months or more	390,443	45,950
Total fair value of unrealized losses on available for sale securities	753,758	489,412
Number of available for sale securities in a continuous unrealized loss position less than twelve months	12	19
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	15	1
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	0	(43)
Unrealized losses on available for sale securities, 12 months or more	0	0
Total unrealized losses on available for sale securities	0	(43)
Fair value of unrealized losses on available for sale securities, less than 12 months	0	6,452
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	$ 0	$ 6,452
Number of available for sale securities in a continuous unrealized loss position less than twelve months	0	5
Number of available for sale securities in a continuous unrealized loss position for twelve months or more	0	0