Expected Loss to be Paid - Net Expected Loss to be Paid After Net Expected Recoveries for Breaches of R&W Rollforward (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	$ 677		$ 1,106
Economic Loss Development After Recoveries for R&W	56		438
(Paid) Recovered Losses After Recoveries for R&W	249	[1]	(867)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	982		677
Period after the end of the reporting period within which the ceded paid losses are typically settled (in days)	45 days
Prime first lien
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	6		2
Economic Loss Development After Recoveries for R&W	16		4
(Paid) Recovered Losses After Recoveries for R&W	(1)	[1]	0	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	21		6
Alt-A first lien
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	315		295
Economic Loss Development After Recoveries for R&W	(81)		62
(Paid) Recovered Losses After Recoveries for R&W	70	[1]	(42)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	304		315
Option ARM
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	(131)		210
Economic Loss Development After Recoveries for R&W	(98)		39
(Paid) Recovered Losses After Recoveries for R&W	220	[1]	(380)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	(9)		(131)
Subprime
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	242		241
Economic Loss Development After Recoveries for R&W	92		49
(Paid) Recovered Losses After Recoveries for R&W	(30)	[1]	(48)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	304		242
Total first lien
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	432		748
Economic Loss Development After Recoveries for R&W	(71)		154
(Paid) Recovered Losses After Recoveries for R&W	259	[1]	(470)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	620		432
Closed-end second lien
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	(39)		(86)
Economic Loss Development After Recoveries for R&W	6		(10)
(Paid) Recovered Losses After Recoveries for R&W	22	[1]	57	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	(11)		(39)
HELOCs
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	(111)		(31)
Economic Loss Development After Recoveries for R&W	(91)		44
(Paid) Recovered Losses After Recoveries for R&W	86	[1]	(124)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	(116)		(111)
Second lien
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	(150)		(117)
Economic Loss Development After Recoveries for R&W	(85)		34
(Paid) Recovered Losses After Recoveries for R&W	108	[1]	(67)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	(127)		(150)
U.S. RMBS
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	282		631
Economic Loss Development After Recoveries for R&W	(156)		188
(Paid) Recovered Losses After Recoveries for R&W	367	[1]	(537)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	493		282
TruPS
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	27		64
Economic Loss Development After Recoveries for R&W	7		(30)
(Paid) Recovered Losses After Recoveries for R&W	17	[1]	(7)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	51		27
Other structured finance
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	312		342
Economic Loss Development After Recoveries for R&W	(41)		2
(Paid) Recovered Losses After Recoveries for R&W	(151)	[1]	(32)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	120		312
U.S. Public Finance
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	7		16
Economic Loss Development After Recoveries for R&W	239		74
(Paid) Recovered Losses After Recoveries for R&W	18	[1]	(83)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	264		7
Non-U.S. public finance
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	52		51
Economic Loss Development After Recoveries for R&W	17		221
(Paid) Recovered Losses After Recoveries for R&W	(12)	[1]	(220)	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	57		52
Other
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	(3)		2
Economic Loss Development After Recoveries for R&W	(10)		(17)
(Paid) Recovered Losses After Recoveries for R&W	10	[1]	12	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	$ (3)		$ (3)

[1] Net of ceded paid losses, whether or not such amounts have been settled with reinsurers. Ceded paid losses are typically settled 45 days after the end of the reporting period. Such amounts are recorded in reinsurance recoverable on paid losses included in other assets.