Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Operating Leases
2020, remaining	$ 135
2021	171
2022	166
2023	115
2024	106
Thereafter	570
Total minimum lease payments	1,263
Less: Amount representing interest	(280)
Present value of minimum lease payments	983
Current	137
Noncurrent	846	$ 882
Finance Leases
2020, remaining	10
2021	13
2022	13
2023	13
2024	14
Thereafter	151
Total minimum lease payments	214
Less: Amount representing interest	(58)
Present value of minimum lease payments	156	$ 157
Current	6
Noncurrent	$ 150