Leases - Additional Information (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($) Lease	Jun. 30, 2019 USD ($) Lease	Dec. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
Operating lease expense	$ 5	$ 10
Operating lease payments	4	8
Operating lease right-of-use asset	5	17
Future Minimum Payments Due	$ 4	$ 4
Lease Term ( in years )	6 years 2 months 12 days	6 years 2 months 12 days
Renewal Term ( in years )	15 years	15 years
Less: imputed interest	$ 11	$ 11
Operating lease liabilities	17	17	$ 0
Operating lease liabilities, noncurrent	$ 55	$ 55	$ 0
Number of leases | Lease	2	2
Lease not yet commenced term (in years)	5 years	5 years
Payments	$ 4	$ 4
Minimum
Operating Leased Assets [Line Items]
Term of Contract ( in years )	1 year	1 year
Maximum
Operating Leased Assets [Line Items]
Term of Contract ( in years )	9 years 3 months 18 days	9 years 3 months 18 days