Fair Values (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Investment securities:
Equity securities	$ 1	$ 1
Debt securities and other	3,946	4,430
Derivatives	922	991
Total assets	4,869	5,422
Level 1 [Member]
Investment securities:
Equity securities	1	1
Debt securities and other	302	350
Derivatives	0	0
Total assets	303	351
Level 2 [Member]
Investment securities:
Equity securities	0	0
Debt securities and other	3,644	4,080
Derivatives	922	991
Total assets	4,566	5,071
Level 3 [Member]
Investment securities:
Equity securities	0	0
Debt securities and other	0	0
Derivatives	0	0
Total assets	$ 0	$ 0