Investment Securities, OTTI Included in Earnings (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
OTTI write-downs included in earnings (Abstract)
Total investment securities	$ 21	$ 13	$ 52	$ 22
Nonmarketable equity investments	75	69	117	195
Total OTTI write-downs included in earnings	96	82	169	217
Total debt securities [Member]
OTTI write-downs included in earnings (Abstract)
Total investment securities	20	13	51	20
Securities of U.S. states and political subdivisions [Member]
OTTI write-downs included in earnings (Abstract)
Total investment securities	0	2	16	2
Residential [Member]
OTTI write-downs included in earnings (Abstract)
Total investment securities	19	5	34	10
Commercial [Member]
OTTI write-downs included in earnings (Abstract)
Total investment securities	0	4	0	6
Total marketable equity securities [Member]
OTTI write-downs included in earnings (Abstract)
Total investment securities	1	0	1	2
Other marketable equity securities [Member]
OTTI write-downs included in earnings (Abstract)
Total investment securities	1	0	1	2
Corporate debt securities [Member]
OTTI write-downs included in earnings (Abstract)
Total investment securities	1	0	1	0
Collateralized Loan Obligations [Member]
OTTI write-downs included in earnings (Abstract)
Total investment securities	$ 0	$ 2	$ 0	$ 2