Leases - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Lease cost:
Amortization of ROU assets	$ 2
Interest on lease liability	1
Finance lease cost	3
Operating lease cost	7
Short-term lease cost	22
Total lease cost	32
Other information:
Operating cash outflows from finance lease	1
Operating cash outflows from operating leases	2
Investing cash outflows from operating leases	27
Financing cash outflows from finance lease	$ 2
Weighted-average remaining lease term - finance lease	2 years 9 months
Weighted-average remaining lease term - operating leases	3 years 9 months 18 days
Weighted-average discount rate - finance lease	7.50%
Weighted-average discount rate - operating leases	5.09%
Capitalized lease costs	$ 27