Investments in Securities Other-than-temporary Impairments 4 (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 8,026
Weighted average collateral default	52.50%	[1]
Weighted average collateral severities	60.00%	[2]
Weighted average voluntary prepayment rates	2.50%	[3]
Average credit enhancement	11.40%	[4]
Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	1,279
Weighted average collateral default	36.70%	[1]
Weighted average collateral severities	50.30%	[2]
Weighted average voluntary prepayment rates	7.00%	[3]
Average credit enhancement	5.20%	[4]
Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	2,141
Weighted average collateral default	17.40%	[1]
Weighted average collateral severities	53.80%	[2]
Weighted average voluntary prepayment rates	11.30%	[3]
Average credit enhancement	4.90%	[4]
Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	1,605
Weighted average collateral default	34.20%	[1]
Weighted average collateral severities	47.30%	[2]
Weighted average voluntary prepayment rates	8.10%	[3]
Average credit enhancement	5.30%	[4]
Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	2,952
Weighted average collateral default	21.50%	[1]
Weighted average collateral severities	43.50%	[2]
Weighted average voluntary prepayment rates	9.60%	[3]
Average credit enhancement	2.90%	[4]
2004 and Prior [Member] | Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	117
Weighted average collateral default	26.50%	[1]
Weighted average collateral severities	55.20%	[2]
Weighted average voluntary prepayment rates	10.10%	[3]
Average credit enhancement	38.40%	[4]
2004 and Prior [Member] | Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	117
Weighted average collateral default	23.90%	[1]
Weighted average collateral severities	54.50%	[2]
Weighted average voluntary prepayment rates	9.70%	[3]
Average credit enhancement	4.10%	[4]
2004 and Prior [Member] | Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	920
Weighted average collateral default	9.50%	[1]
Weighted average collateral severities	52.00%	[2]
Weighted average voluntary prepayment rates	13.40%	[3]
Average credit enhancement	10.90%	[4]
2004 and Prior [Member] | Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	133
Weighted average collateral default	20.80%	[1]
Weighted average collateral severities	40.80%	[2]
Weighted average voluntary prepayment rates	9.90%	[3]
Average credit enhancement	21.30%	[4]
2004 and Prior [Member] | Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	328
Weighted average collateral default	13.30%	[1]
Weighted average collateral severities	38.50%	[2]
Weighted average voluntary prepayment rates	10.20%	[3]
Average credit enhancement	9.40%	[4]
2005 [Member] | Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	41
Weighted average collateral default	49.00%	[1]
Weighted average collateral severities	60.00%	[2]
Weighted average voluntary prepayment rates	2.90%	[3]
Average credit enhancement	47.90%	[4]
2005 [Member] | Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	472
Weighted average collateral default	31.90%	[1]
Weighted average collateral severities	53.50%	[2]
Weighted average voluntary prepayment rates	7.50%	[3]
Average credit enhancement	8.90%	[4]
2005 [Member] | Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	828
Weighted average collateral default	22.90%	[1]
Weighted average collateral severities	54.00%	[2]
Weighted average voluntary prepayment rates	10.40%	[3]
Average credit enhancement	0.60%	[4]
2005 [Member] | Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	384
Weighted average collateral default	33.00%	[1]
Weighted average collateral severities	47.70%	[2]
Weighted average voluntary prepayment rates	8.50%	[3]
Average credit enhancement	12.60%	[4]
2005 [Member] | Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	1,348
Weighted average collateral default	26.40%	[1]
Weighted average collateral severities	44.20%	[2]
Weighted average voluntary prepayment rates	9.10%	[3]
Average credit enhancement	2.80%	[4]
2006 [Member] | Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	7,527
Weighted average collateral default	0.00%	[1]
Weighted average collateral severities	61.40%	[2]
Weighted average voluntary prepayment rates	2.40%	[3]
Average credit enhancement	10.30%	[4]
2006 [Member] | Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	690
Weighted average collateral default	0.00%	[1]
Weighted average collateral severities	48.30%	[2]
Weighted average voluntary prepayment rates	6.10%	[3]
Average credit enhancement	2.90%	[4]
2006 [Member] | Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	393
Weighted average collateral default	0.00%	[1]
Weighted average collateral severities	55.20%	[2]
Weighted average voluntary prepayment rates	8.30%	[3]
Average credit enhancement	0.10%	[4]
2006 [Member] | Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	1,088
Weighted average collateral default	0.00%	[1]
Weighted average collateral severities	47.70%	[2]
Weighted average voluntary prepayment rates	7.70%	[3]
Average credit enhancement	0.70%	[4]
2006 [Member] | Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	1,193
Weighted average collateral default	0.00%	[1]
Weighted average collateral severities	43.70%	[2]
Weighted average voluntary prepayment rates	10.10%	[3]
Average credit enhancement	0.00%	[4]
2007 and After [Member] | Subprime private-label securities [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	341
Weighted average collateral default	50.40%	[1]
Weighted average collateral severities	28.00%	[2]
Weighted average voluntary prepayment rates	1.40%	[3]
Average credit enhancement	20.30%	[4]
2007 and After [Member] | Alt-A Option ARM [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	0
2007 and After [Member] | Alt-A Fixed Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	0
2007 and After [Member] | Alt-A Variable Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	0
2007 and After [Member] | Alt-A Hybrid Rate [Member]
UPB and Modeled Attributes [Line Items]
Unpaid principal balance	$ 83
Weighted average collateral default	21.90%	[1]
Weighted average collateral severities	39.90%	[2]
Weighted average voluntary prepayment rates	9.90%	[3]
Average credit enhancement	20.40%	[4]

[1] The expected remaining cumulative default rate of the collateral pool backing the securities, as a percentage of the current collateral unpaid principal balance, weighted by security unpaid principal balance.

[2] The expected remaining loss given default of the collateral pool backing the securities, calculated as the ratio of remaining cumulative loss divided by cumulative defaults, weighted by security unpaid principal balance.

[3] The average monthly voluntary prepayment rate, weighted by security unpaid principal balance.

[4] The average percent current credit enhancement provided by subordination of other securities. Excludes excess interest projections and monoline bond insurance.