Leases - Maturities of Lease Liabilities (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
2019 (remaining)	$ 48
2020	70
2021	59
2022	56
2023	53
Thereafter	290
Total future minimum lease payments	576
Less imputed interest	(133)
Total operating lease liabilities	443
Finance Lease Liabilities, Payments, Due [Abstract]
2019 (remaining)	3
2020	2
2021	1
2022	0
2023	0
Thereafter	0
Total future minimum lease payments	6
Less imputed interest	(1)
Total finance lease liabilities	$ 5