Leases - Maturities of Lease Liabilities (Details) $ in Millions	Sep. 30, 2019 USD ($)
Operating Leases Future Minimum Rental Payments
Remainder of 2019	$ 27
2020	154
2021	139
2022	123
2023	108
Thereafter	788
Total lease payments	1,339
Less: Imputed interest	371
Present value of lease liabilities	968
Finance Leases
Remainder of 2019	0
2020	1
2021	0
2022	0
2023	1
Thereafter	11
Total lease payments	13
Less: Imputed interest	9
Present value of lease liabilities	4
Legally binding lease payments for leases signed but not yet commenced	$ 11