Investment Securities, OTTI Debt Securities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	$ 21	$ 13	$ 52	$ 22
Cost And Equity Method, Other Than Temporary Impairment	75	69	117	195
Other Than Temporary Impairment Investments Portion Recognized In Earnings Net	96	82	169	217
Total debt securities [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	20	13	51	20
Total changes to OCI for non-credit-related OTTI	(10)	(10)	(47)	(31)
Total OTTI losses (reversal of losses) recorded on debt securities	10	3	4	(11)
Total debt securities [Member] | Credit-related OTTI [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	19	9	39	16
Total debt securities [Member] | Intent-to-sell OTTI [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	1	4	12	4
Securities of U.S. states and political subdivisions [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	0	2	16	2
Total changes to OCI for non-credit-related OTTI	0	1	(1)	1
Residential [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	19	5	34	10
Total changes to OCI for non-credit-related OTTI	(10)	(4)	(31)	(13)
Commercial Mortgage Backed Securities [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	0	4	0	6
Total changes to OCI for non-credit-related OTTI	0	(7)	(15)	(19)
Corporate debt securities [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	1	0	1	0
Collateralized Loan Obligations [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	0	2	0	2
Other [Member]
OTTI on debt securities (Abstract)
Total changes to OCI for non-credit-related OTTI	0	(1)	0	0
Equity Securities, Other 1 [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	1	0	1	2
Equity Securities [Member]
OTTI on debt securities (Abstract)
Total recorded as part of gross realized losses	$ 1	$ 0	$ 1	$ 2