Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Operating Leases
2019, remaining	$ 44
2020	172
2021	156
2022	148
2023	113
Thereafter	666
Total minimum lease payments	1,299
Less: Amount representing interest	(300)
Present value of minimum lease payments	999
Current	131
Noncurrent	868	$ 0
Finance Leases
2019, remaining	3
2020	13
2021	13
2022	13
2023	13
Thereafter	165
Total minimum lease payments	220
Less: Amount representing interest	(61)
Present value of minimum lease payments	159	$ 163
Current	6
Noncurrent	$ 153
Operating leases	4.90%
Finance leases	4.40%
Operating leases	11 years
Finance leases	15 years