Leases - Summary of Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Rental costs	$ 4	$ 7	$ 15	$ 23
Weighted average lease term (in years)	7 years		7 years
Weighted average discount rate (as a percentage)	5.47%		5.47%
Operating lease cost	$ 2	2	$ 5	7
Short-term lease cost	2	4	9	15
Variable Lease, Cost	0	1	1	1
Total Lease Cost	4	7	15	23
Transportation and Storage
Lessee, Lease, Description [Line Items]
Short-term lease cost				1
Field equipment
Lessee, Lease, Description [Line Items]
Rental costs	3	6	12	18
Total Lease Cost	3	6	12	18
Buildings
Lessee, Lease, Description [Line Items]
Rental costs	1	1	3	5
Total Lease Cost	$ 1	$ 1	$ 3	$ 5