Securities - Changes in Credit Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Changes in the credit loss component of OTTI losses recognized in income related to AFS debt securities
Balance, beginning of period	$ 4	$ 1	$ 3	$ 1
Additions:
Newly credit-impaired securities	0	0	1	0
Balance, end of period	$ 4	$ 1	$ 4	$ 1