Leases - Components of Lease Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 170	$ 190	$ 188
Finance lease cost:
Amortization of ROU assets	22	28	28
Interest on lease liabilities	2	3	3
Total finance lease cost	24	31	31
Variable lease cost	39	48	50
Total lease cost	$ 233	$ 269	$ 269