Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Property, plant and equipment	$ 238	$ 157
Net operating loss carryovers	642	611
Employee benefits	1	2
Lease obligations	4
Legal and other reserves	17	9
Asset retirement obligations	10	9
Interest deduction limitation	125	76
Transaction costs	33	14
Total deferred tax assets	1,070	878
Valuation allowance	(1,064)	(857)
Net deferred tax assets	6	21
Deferred tax liabilities
Operating lease assets	4
Financial derivatives	2	21
Total deferred tax liabilities	6	21
Net deferred tax liabilities	$ 0	$ 0