Fair Values (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Investment securities:
Equity securities	$ 1	$ 1
Debt securities and other	3,838	3,758
Derivatives	624	544
Total assets	4,463	4,303
Level 1 [Member]
Investment securities:
Equity securities	1	1
Debt securities and other	385	409
Derivatives	0	0
Total assets	386	410
Level 2 [Member]
Investment securities:
Equity securities	0	0
Debt securities and other	3,453	3,349
Derivatives	624	544
Total assets	4,077	3,893
Level 3 [Member]
Investment securities:
Equity securities	0	0
Debt securities and other	0	0
Derivatives	0	0
Total assets	$ 0	$ 0