Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current	$ 22	$ 148	$ 71	$ 213
Deferred	(115)	(285)	(988)	(699)
Total Income Tax Benefit	$ (93)	$ (137)	$ (917)	$ (486)
Effective Tax Rate	44.70%	48.90%	36.90%	39.50%
Foreign Loss Carryforward
Operating Loss Carryforwards [Line Items]
Deferred tax assets, valuation allowance	$ 181		$ 181		$ 242