Investments in Securities Other-than-temporary Impairments 2 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Net other-than-temporary impairments	$ 12	$ 38	$ 599	$ 64	$ (54)	$ 262	$ 56	$ 44	$ 713	$ 308	$ 722	[1]
Alt-A private-label securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Net other-than-temporary impairments									365	563	327	[1]
Subprime private-label securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Net other-than-temporary impairments									329	(303)	368	[1]
Other mortgage-related securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Net other-than-temporary impairments									$ 19	$ 48	$ 27	[1]

[1] Certain prior period amounts have been reclassified to conform to the current period presentation.