Leases - Supplemental Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating cash flows for operating leases	$ 525	$ 566
Operating cash flows for finance leases	15	14
Financing cash flows for finance leases	52	40
Operating lease right-of-use assets obtained in exchange for new operating lease liabilities	165	375
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 94	$ 124