Details of Certain Items Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, Available-for-sale, USD $) In Millions, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	$ 83,374		$ 78,467
Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	284	[1]	273	[1]
Alt-A RMBS | 2006-2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	110	[1]	99	[1]
Alt-A RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	110	[1]	113	[1]
Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	64	[1]	61	[1]
Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	811	[1]	815	[1]
Prime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	115	[1]	121	[1]
Prime RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	74	[1]	75	[1]
Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	237	[1]	230	[1]
Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	385	[1]	389	[1]
Subprime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	421	[1]	418	[1]
Subprime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2	[1]	2	[1]
Subprime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	89	[1]	82	[1]
Subprime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	330	[1]	334	[1]
Commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	3,482		3,339
Commercial MBS | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	3,162	[1]	3,005	[1]
Commercial MBS | 2009-2012 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	238	[1]	200	[1]
Commercial MBS | 2008 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	25	[1]	25	[1]
Commercial MBS | 2007 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	832	[1]	789	[1]
Commercial MBS | 2006 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	937	[1]	892	[1]
Commercial MBS | 2005 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	721	[1]	696	[1]
Commercial MBS | 2004 and earlier | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	409	[1]	403	[1]
Foreign Covered Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	3,207	[1]	2,425	[1]
Foreign Covered Bonds | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	1,515	[1]	1,461	[1]
Foreign Covered Bonds | Canada
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	955	[1]	795	[1]
Foreign Covered Bonds | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	737	[1]	169	[1]
European Floating Rate Notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	1,868	[1]	1,429	[1]
European Floating Rate Notes | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	71	[1]	93	[1]
European Floating Rate Notes | United Kingdom
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	855	[1]	686	[1]
European Floating Rate Notes | Netherlands
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	335	[1]	47	[1]
European Floating Rate Notes | Ireland
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	208	[1]	203	[1]
European Floating Rate Notes | Italy
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	148	[1]	150	[1]
European Floating Rate Notes | Luxembourg
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	146	[1]	140	[1]
European Floating Rate Notes | Australia
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	95	[1]	101	[1]
European Floating Rate Notes | France
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	10	[1]	9	[1]
Sovereign Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	12,208	[1]	11,954	[1]
Sovereign Debt | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	1,625	[1]	2,347	[1]
Sovereign Debt | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	56	[1]	61	[1]
Sovereign Debt | United Kingdom
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	4,743	[1]	4,526	[1]
Sovereign Debt | Netherlands
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	3,590	[1]	2,230	[1]
Sovereign Debt | France
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,194	[1]	2,790	[1]
Grantor Trust Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	1,962	[1],[2]	1,879	[1],[2]
Grantor Trust Alt-A RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	584	[1],[2]	554	[1],[2]
Grantor Trust Alt-A RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	521	[1],[2]	488	[1],[2]
Grantor Trust Alt-A RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	643	[1],[2]	628	[1],[2]
Grantor Trust Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	214	[1],[2]	209	[1],[2]
Grantor Trust Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	1,153	[1],[2]	1,175	[1],[2]
Grantor Trust Prime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	361	[1],[2]	370	[1],[2]
Grantor Trust Prime RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	306	[1],[2]	308	[1],[2]
Grantor Trust Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	452	[1],[2]	465	[1],[2]
Grantor Trust Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	34	[1],[2]	32	[1],[2]
Grantor Trust Sub Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	117	[1],[2]	125	[1],[2]
Grantor Trust Sub Prime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	4	[1],[2]	3	[1],[2]
Grantor Trust Sub Prime RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	66	[1],[2]	74	[1],[2]
Grantor Trust Sub Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	11	[1],[2]	11	[1],[2]
Grantor Trust Sub Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	$ 36	[1],[2]	$ 37	[1],[2]
Ratings, AAA/AA- | Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	6.00%		6.00%
Ratings, AAA/AA- | Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	26.00%		27.00%
Ratings, AAA/AA- | Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	28.00%		28.00%
Ratings, AAA/AA- | Prime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	42.00%		38.00%
Ratings, AAA/AA- | Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	32.00%		32.00%
Ratings, AAA/AA- | Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	27.00%		29.00%
Ratings, AAA/AA- | Subprime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	8.00%		8.00%
Ratings, AAA/AA- | Subprime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	23.00%		23.00%
Ratings, AAA/AA- | Subprime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	4.00%		5.00%
Ratings, AAA/AA- | Commercial MBS | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	82.00%		84.00%
Ratings, AAA/AA- | Commercial MBS | 2009-2012 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Commercial MBS | 2008 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	16.00%		16.00%
Ratings, AAA/AA- | Commercial MBS | 2007 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	60.00%		66.00%
Ratings, AAA/AA- | Commercial MBS | 2006 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	83.00%		85.00%
Ratings, AAA/AA- | Commercial MBS | 2005 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	94.00%		94.00%
Ratings, AAA/AA- | Commercial MBS | 2004 and earlier | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	96.00%		97.00%
Ratings, AAA/AA- | Foreign Covered Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Foreign Covered Bonds | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	99.00%		99.00%
Ratings, AAA/AA- | Foreign Covered Bonds | Canada
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Foreign Covered Bonds | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | European Floating Rate Notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	60.00%		55.00%
Ratings, AAA/AA- | European Floating Rate Notes | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value			21.00%
Ratings, AAA/AA- | European Floating Rate Notes | United Kingdom
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	64.00%		72.00%
Ratings, AAA/AA- | European Floating Rate Notes | Netherlands
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	90.00%		35.00%
Ratings, AAA/AA- | European Floating Rate Notes | Ireland
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	12.00%
Ratings, AAA/AA- | European Floating Rate Notes | Italy
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | European Floating Rate Notes | Australia
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	92.00%		91.00%
Ratings, AAA/AA- | European Floating Rate Notes | France
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Sovereign Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Sovereign Debt | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Sovereign Debt | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	98.00%		97.00%
Ratings, AAA/AA- | Sovereign Debt | United Kingdom
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Sovereign Debt | Netherlands
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Sovereign Debt | France
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, AAA/AA- | Grantor Trust Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	2.00%	[2]	2.00%	[2]
Ratings, AAA/AA- | Grantor Trust Alt-A RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	4.00%	[2]	5.00%	[2]
Ratings, AAA/AA- | Grantor Trust Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	1.00%	[2]
Ratings, AAA/AA- | Grantor Trust Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	8.00%	[2]	9.00%	[2]
Ratings, AAA/AA- | Grantor Trust Sub Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	2.00%	[2]	2.00%	[2]
Ratings, AAA/AA- | Grantor Trust Sub Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	5.00%	[2]	5.00%	[2]
Ratings, A+/A- | Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	3.00%		3.00%
Ratings, A+/A- | Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	13.00%		13.00%
Ratings, A+/A- | Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	19.00%		19.00%
Ratings, A+/A- | Prime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	4.00%		4.00%
Ratings, A+/A- | Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	39.00%		38.00%
Ratings, A+/A- | Subprime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	14.00%		14.00%
Ratings, A+/A- | Subprime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value			2.00%
Ratings, A+/A- | Subprime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	12.00%		12.00%
Ratings, A+/A- | Subprime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	15.00%		15.00%
Ratings, A+/A- | Commercial MBS | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	16.00%		14.00%
Ratings, A+/A- | Commercial MBS | 2008 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	84.00%		84.00%
Ratings, A+/A- | Commercial MBS | 2007 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	32.00%		26.00%
Ratings, A+/A- | Commercial MBS | 2006 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	17.00%		15.00%
Ratings, A+/A- | Commercial MBS | 2005 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	6.00%		6.00%
Ratings, A+/A- | Commercial MBS | 2004 and earlier | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	3.00%		2.00%
Ratings, A+/A- | Foreign Covered Bonds | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	1.00%		1.00%
Ratings, A+/A- | European Floating Rate Notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	27.00%		34.00%
Ratings, A+/A- | European Floating Rate Notes | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	8.00%		6.00%
Ratings, A+/A- | European Floating Rate Notes | United Kingdom
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	36.00%		28.00%
Ratings, A+/A- | European Floating Rate Notes | Netherlands
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	10.00%		65.00%
Ratings, A+/A- | European Floating Rate Notes | Ireland
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value			50.00%
Ratings, A+/A- | European Floating Rate Notes | Luxembourg
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, A+/A- | European Floating Rate Notes | Australia
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	8.00%		9.00%
Ratings, A+/A- | Sovereign Debt | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	2.00%		3.00%
Ratings, A+/A- | Grantor Trust Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	4.00%	[2]	4.00%	[2]
Ratings, A+/A- | Grantor Trust Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	1.00%	[2]	2.00%	[2]
Ratings, A+/A- | Grantor Trust Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	3.00%	[2]	4.00%	[2]
Ratings, A+/A- | Grantor Trust Sub Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	10.00%	[2]	10.00%	[2]
Ratings, A+/A- | Grantor Trust Sub Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	34.00%	[2]	34.00%	[2]
Ratings, BBB+/BBB- | Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	11.00%		11.00%
Ratings, BBB+/BBB- | Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	48.00%		47.00%
Ratings, BBB+/BBB- | Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	6.00%		5.00%
Ratings, BBB+/BBB- | Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	12.00%		11.00%
Ratings, BBB+/BBB- | Subprime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	21.00%		21.00%
Ratings, BBB+/BBB- | Subprime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		98.00%
Ratings, BBB+/BBB- | Subprime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	27.00%		29.00%
Ratings, BBB+/BBB- | Subprime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	19.00%		18.00%
Ratings, BBB+/BBB- | Commercial MBS | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	2.00%		2.00%
Ratings, BBB+/BBB- | Commercial MBS | 2007 | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	8.00%		8.00%
Ratings, BBB+/BBB- | Commercial MBS | 2004 and earlier | Domestic
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	1.00%		1.00%
Ratings, BBB+/BBB- | European Floating Rate Notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	8.00%		11.00%
Ratings, BBB+/BBB- | European Floating Rate Notes | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	91.00%		73.00%
Ratings, BBB+/BBB- | European Floating Rate Notes | Ireland
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	46.00%		47.00%
Ratings, BBB+/BBB- | Grantor Trust Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	3.00%	[2]	3.00%	[2]
Ratings, BBB+/BBB- | Grantor Trust Alt-A RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	1.00%	[2]	1.00%	[2]
Ratings, BBB+/BBB- | Grantor Trust Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	26.00%	[2]	27.00%	[2]
Ratings, BBB+/BBB- | Grantor Trust Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	1.00%	[2]	1.00%	[2]
Ratings, BBB+/BBB- | Grantor Trust Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	22.00%	[2]	22.00%	[2]
Ratings, BB+ and lower | Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	80.00%		80.00%
Ratings, BB+ and lower | Alt-A RMBS | 2006-2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, BB+ and lower | Alt-A RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, BB+ and lower | Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	13.00%		13.00%
Ratings, BB+ and lower | Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	47.00%		48.00%
Ratings, BB+ and lower | Prime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	54.00%		58.00%
Ratings, BB+ and lower | Prime RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%		100.00%
Ratings, BB+ and lower | Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	68.00%		68.00%
Ratings, BB+ and lower | Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	22.00%		22.00%
Ratings, BB+ and lower | Subprime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	57.00%		57.00%
Ratings, BB+ and lower | Subprime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	38.00%		36.00%
Ratings, BB+ and lower | Subprime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	62.00%		62.00%
Ratings, BB+ and lower | European Floating Rate Notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	5.00%
Ratings, BB+ and lower | European Floating Rate Notes | Germany
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	1.00%
Ratings, BB+ and lower | European Floating Rate Notes | Ireland
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	42.00%		3.00%
Ratings, BB+ and lower | Grantor Trust Alt-A RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	95.00%	[2]	95.00%	[2]
Ratings, BB+ and lower | Grantor Trust Alt-A RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%	[2]	100.00%	[2]
Ratings, BB+ and lower | Grantor Trust Alt-A RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%	[2]	100.00%	[2]
Ratings, BB+ and lower | Grantor Trust Alt-A RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	95.00%	[2]	94.00%	[2]
Ratings, BB+ and lower | Grantor Trust Alt-A RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	70.00%	[2]	69.00%	[2]
Ratings, BB+ and lower | Grantor Trust Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	98.00%	[2]	97.00%	[2]
Ratings, BB+ and lower | Grantor Trust Prime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%	[2]	100.00%	[2]
Ratings, BB+ and lower | Grantor Trust Prime RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%	[2]	100.00%	[2]
Ratings, BB+ and lower | Grantor Trust Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	96.00%	[2]	96.00%	[2]
Ratings, BB+ and lower | Grantor Trust Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	70.00%	[2]	69.00%	[2]
Ratings, BB+ and lower | Grantor Trust Sub Prime RMBS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	88.00%	[2]	88.00%	[2]
Ratings, BB+ and lower | Grantor Trust Sub Prime RMBS | 2007
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%	[2]	100.00%	[2]
Ratings, BB+ and lower | Grantor Trust Sub Prime RMBS | 2006
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%	[2]	100.00%	[2]
Ratings, BB+ and lower | Grantor Trust Sub Prime RMBS | 2005
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	100.00%	[2]	100.00%	[2]
Ratings, BB+ and lower | Grantor Trust Sub Prime RMBS | 2004 and earlier
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Percentage of fair value	61.00%	[2]	61.00%	[2]

[1] At March 31, 2012 and Dec. 31, 2011, the German foreign covered bonds were considered Level 1 in the valuation hierarchy. All other assets in the table above are primarily Level 2 assets in the valuation hierarchy.

[2] Previously included in the Grantor Trust.