Leases - Components of Lease Cost and Rent Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 196	$ 203	$ 194
Short-term rent expense	92	104	114
Variable lease cost	25	26	18
Sublease income	(5)	(6)	(5)
Total operating lease cost	308	327	321
Finance lease cost:
Amortization of ROU assets	9	10	12
Interest on finance lease liabilities	9	8	7
Total finance lease cost	$ 18	$ 18	$ 19