Expected Loss to be Paid - Net Expected Recoveries from Breaches of R&W Rollforward (Details) (RMBS [Member], United States [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	$ 712		$ 1,370
R&W development and accretion of discount during period	268		296
R&W recovered during period	(663)		(954)
Future net R&W benefit at the end of the period	317	[1]	712
First Lien [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	569		1,082
R&W development and accretion of discount during period	194		211
R&W recovered during period	(531)		(724)
Future net R&W benefit at the end of the period	232	[1]	569
First Lien [Member] | Prime [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	4		4
R&W development and accretion of discount during period	(1)		0
R&W recovered during period	(1)		0
Future net R&W benefit at the end of the period	2	[1]	4
First Lien [Member] | Alt-A [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	274		378
R&W development and accretion of discount during period	131		41
R&W recovered during period	(299)		(145)
Future net R&W benefit at the end of the period	106	[1]	274
First Lien [Member] | Option ARM [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	173		591
R&W development and accretion of discount during period	14		161
R&W recovered during period	(172)		(579)
Future net R&W benefit at the end of the period	15	[1]	173
First Lien [Member] | Subprime [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	118		109
R&W development and accretion of discount during period	50		9
R&W recovered during period	(59)		0
Future net R&W benefit at the end of the period	109	[1]	118
Second Lien [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	143		288
R&W development and accretion of discount during period	74		85
R&W recovered during period	(132)		(230)
Future net R&W benefit at the end of the period	85	[1]	143
Second Lien [Member] | Closed-end [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	98		138
R&W development and accretion of discount during period	(6)		(9)
R&W recovered during period	(7)		(31)
Future net R&W benefit at the end of the period	85	[1]	98
Second Lien [Member] | HELOCs [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	45		150
R&W development and accretion of discount during period	80		94
R&W recovered during period	(125)		(199)
Future net R&W benefit at the end of the period	$ 0	[1]	$ 45

[1] See the section "Breaches of Representations and Warranties" below for eligible assets held in trust.