Income Taxes Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income tax (benefit) expense	$ 8	$ (16)	$ 14	$ 1
Income (loss) from continuing operations before income tax benefit (expense)	$ (565)	$ 394	$ (1,223)	$ 778
Effective income tax rate	(1.40%)	(4.10%)	(1.10%)	0.10%
Statutory federal income tax rate			21.00%	21.00%