Leases - Additional Information (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Lease cost:
Amortization of ROU assets	$ 2	$ 4
Interest on lease liability	0	1
Finance lease cost	2	5
Operating lease cost	10	17
Short-term lease cost	26	48
Total lease cost	38	70
Other information:
Operating cash outflows from finance lease	0	1
Operating cash outflows from operating leases	3	5
Investing cash outflows from operating leases	33	60
Financing cash outflows from finance lease	$ 2	$ 4
Weighted-average remaining lease term - finance lease	2 years 6 months	2 years 6 months
Weighted-average remaining lease term - operating leases	4 years 6 months	4 years 6 months
Weighted-average discount rate - finance lease	7.50%	7.50%
Weighted-average discount rate - operating leases	4.83%	4.83%
Capitalized lease costs	$ 33	$ 60