Investments in Securities Other-than-temporary Impairments 1 (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]
OTTI recognized in Investment gains, net	$ 5	$ 6	$ 187	$ 80
Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Total unpaid principal balance	$ 4,917		$ 4,917
Weighted average collateral default	42.40%		42.40%
Weighted average collateral severities	60.00%		60.00%
Weighted average voluntary prepayment rates	2.70%		2.70%
Average credit enhancement	17.40%		17.40%
Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Total unpaid principal balance	$ 494		$ 494
Weighted average collateral default	29.40%		29.40%
Weighted average collateral severities	38.50%		38.50%
Weighted average voluntary prepayment rates	7.40%		7.40%
Average credit enhancement	3.60%		3.60%
Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Total unpaid principal balance	$ 1,205		$ 1,205
Weighted average collateral default	11.90%		11.90%
Weighted average collateral severities	46.90%		46.90%
Weighted average voluntary prepayment rates	12.20%		12.20%
Average credit enhancement	5.60%		5.60%
Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Total unpaid principal balance	$ 838		$ 838
Weighted average collateral default	21.40%		21.40%
Weighted average collateral severities	37.90%		37.90%
Weighted average voluntary prepayment rates	8.40%		8.40%
Average credit enhancement	8.60%		8.60%
Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Total unpaid principal balance	$ 1,237		$ 1,237
Weighted average collateral default	10.00%		10.00%
Weighted average collateral severities	34.20%		34.20%
Weighted average voluntary prepayment rates	12.00%		12.00%
Average credit enhancement	4.40%		4.40%