Income Taxes - Income Tax Benefit/(Provision) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Current - Federal	$ 0	$ 0	$ 7
Current - State	0	110	83
Deferred - Federal	135	593	1,388
Deferred - State	(10)	(109)	51
Current - Ouside of the U.S.	(78)	(56)	(29)
Deferred - Ouside of the U.S.	8	5	17
Total income tax benefit	$ 55	$ 543	$ 1,517