Leases - Summary of Operating and Finance Lease Maturities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating
2020	$ 188
2021	162
2022	146
2023	98
2024	45
Thereafter	78
Total lease payments	717
Less interest	(56)
Present value of lease liabilities	661
Finance
2020	12
2021	12
2022	5
2023	0
2024	0
Thereafter	0
Total lease payments	29
Less interest	(2)
Present value of lease liabilities	27
Rent expense	$ 233	$ 118	$ 105