Securities Available for Sale, Other-Than-Temporary Impaired Debt Securities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	$ 38	$ 51
Debt Securities [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	34	50
Total changes to OCI for non-credit-related OTTI	(49)	(15)
Total OTTI losses (gains) recorded on debt securities	(15)	35
Debt Securities [Member] \| Credit-related OTTI [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	23	50
Debt Securities [Member] \| Intent-to-sell OTTI [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	11	0
US States and Political Subdivisions [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	0	0
Total changes to OCI for non-credit-related OTTI	0	0
Residential [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	15	14
Total changes to OCI for non-credit-related OTTI	(9)	(9)
Commercial [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	15	30
Total changes to OCI for non-credit-related OTTI	(41)	(6)
Collateralized loan and other debt obligations [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	0	0
Total changes to OCI for non-credit-related OTTI	(1)	0
Other Debt Securities [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	2	5
Total changes to OCI for non-credit-related OTTI	2	1
Corporate debt securities [Member]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total OTTI recorded as part of gross realized losses	2	1
Total changes to OCI for non-credit-related OTTI	$ 0	$ (1)

The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis.

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