Income Taxes - Components of Income Tax (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Current	$ 24	$ 45	$ 61	$ 194
Deferred	(9)	14	(110)	(150)
Total Income Tax Expense (Benefit)	$ 15	$ 59	$ (49)	$ 44
Effective Tax Rate	29.40%	19.20%	16.70%	5.10%