Income Taxes - Components of Deferred Provision (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Deferred income tax provision (excluding the effects of other components)	$ 201	$ 144	$ 31
Increase in Federal operating loss carryforwards	0	1	0
(Decrease) increase in State valuation allowance	(5)	11	0
Increase in State capital loss carryforwards	(6)	0	0
(Increase) decrease in foreign and general business tax credits	0	29	(29)
Deferred income tax provision (benefit)	$ 190	$ 185	$ 2