Investments in Securities Other-than-temporary Impairments 1 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investments, Debt and Equity Securities [Abstract]
OTTI recognized in Investment gains, net	$ 12	$ 23	$ 182	$ 74
Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 5,064		$ 5,064
Weighted average collateral default	44.20%		44.20%
Weighted average collateral severities	60.10%		60.10%
Weighted average voluntary prepayment rates	2.60%		2.60%
Average credit enhancement	17.70%		17.70%
Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 516		$ 516
Weighted average collateral default	32.10%		32.10%
Weighted average collateral severities	40.00%		40.00%
Weighted average voluntary prepayment rates	6.90%		6.90%
Average credit enhancement	3.70%		3.70%
Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 1,375		$ 1,375
Weighted average collateral default	11.80%		11.80%
Weighted average collateral severities	47.30%		47.30%
Weighted average voluntary prepayment rates	11.70%		11.70%
Average credit enhancement	6.00%		6.00%
Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 870		$ 870
Weighted average collateral default	22.10%		22.10%
Weighted average collateral severities	38.50%		38.50%
Weighted average voluntary prepayment rates	8.30%		8.30%
Average credit enhancement	8.40%		8.40%
Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 1,297		$ 1,297
Weighted average collateral default	10.40%		10.40%
Weighted average collateral severities	34.30%		34.30%
Weighted average voluntary prepayment rates	11.70%		11.70%
Average credit enhancement	4.40%		4.40%
2004 and Prior [Member] | Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 99		$ 99
Weighted average collateral default	25.10%		25.10%
Weighted average collateral severities	53.50%		53.50%
Weighted average voluntary prepayment rates	8.00%		8.00%
Average credit enhancement	38.80%		38.80%
2004 and Prior [Member] | Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 12		$ 12
Weighted average collateral default	22.80%		22.80%
Weighted average collateral severities	57.20%		57.20%
Weighted average voluntary prepayment rates	10.70%		10.70%
Average credit enhancement	16.60%		16.60%
2004 and Prior [Member] | Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 711		$ 711
Weighted average collateral default	7.80%		7.80%
Weighted average collateral severities	42.60%		42.60%
Weighted average voluntary prepayment rates	13.50%		13.50%
Average credit enhancement	11.00%		11.00%
2004 and Prior [Member] | Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 109		$ 109
Weighted average collateral default	15.80%		15.80%
Weighted average collateral severities	35.90%		35.90%
Weighted average voluntary prepayment rates	9.50%		9.50%
Average credit enhancement	25.40%		25.40%
2004 and Prior [Member] | Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 268		$ 268
Weighted average collateral default	10.60%		10.60%
Weighted average collateral severities	29.90%		29.90%
Weighted average voluntary prepayment rates	10.70%		10.70%
Average credit enhancement	10.60%		10.60%
2005 [Member] | Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 7		$ 7
Weighted average collateral default	43.00%		43.00%
Weighted average collateral severities	61.80%		61.80%
Weighted average voluntary prepayment rates	4.10%		4.10%
Average credit enhancement	57.20%		57.20%
2005 [Member] | Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 197		$ 197
Weighted average collateral default	29.30%		29.30%
Weighted average collateral severities	53.00%		53.00%
Weighted average voluntary prepayment rates	7.00%		7.00%
Average credit enhancement	8.60%		8.60%
2005 [Member] | Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 312		$ 312
Weighted average collateral default	12.20%		12.20%
Weighted average collateral severities	47.90%		47.90%
Weighted average voluntary prepayment rates	11.90%		11.90%
Average credit enhancement	1.30%		1.30%
2005 [Member] | Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 124		$ 124
Weighted average collateral default	25.00%		25.00%
Weighted average collateral severities	52.90%		52.90%
Weighted average voluntary prepayment rates	8.60%		8.60%
Average credit enhancement	29.00%		29.00%
2005 [Member] | Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 324		$ 324
Weighted average collateral default	14.40%		14.40%
Weighted average collateral severities	37.10%		37.10%
Weighted average voluntary prepayment rates	10.10%		10.10%
Average credit enhancement	8.70%		8.70%
2006 [Member] | Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 4,765		$ 4,765
Weighted average collateral default	44.80%		44.80%
Weighted average collateral severities	61.90%		61.90%
Weighted average voluntary prepayment rates	2.60%		2.60%
Average credit enhancement	16.80%		16.80%
2006 [Member] | Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 307		$ 307
Weighted average collateral default	34.20%		34.20%
Weighted average collateral severities	32.50%		32.50%
Weighted average voluntary prepayment rates	6.60%		6.60%
Average credit enhancement	0.00%		0.00%
2006 [Member] | Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 352		$ 352
Weighted average collateral default	19.70%		19.70%
Weighted average collateral severities	50.70%		50.70%
Weighted average voluntary prepayment rates	8.00%		8.00%
Average credit enhancement	0.00%		0.00%
2006 [Member] | Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 637		$ 637
Weighted average collateral default	22.60%		22.60%
Weighted average collateral severities	35.70%		35.70%
Weighted average voluntary prepayment rates	8.00%		8.00%
Average credit enhancement	1.50%		1.50%
2006 [Member] | Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 705		$ 705
Weighted average collateral default	8.60%		8.60%
Weighted average collateral severities	34.20%		34.20%
Weighted average voluntary prepayment rates	12.80%		12.80%
Average credit enhancement	0.00%		0.00%
2007 and After [Member] | Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 193		$ 193
Weighted average collateral default	40.10%		40.10%
Weighted average collateral severities	12.40%		12.40%
Weighted average voluntary prepayment rates	1.60%		1.60%
Average credit enhancement	27.70%		27.70%
2007 and After [Member] | Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 0		$ 0
2007 and After [Member] | Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	0		0
2007 and After [Member] | Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	0		0
2007 and After [Member] | Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 0		$ 0