Leases (Other Information) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 162	$ 156
Operating cash flows from finance leases	3	9
Financing cash flows from finance leases	55	39
Leased assets obtained in exchange for new operating lease liabilities	241	135
Leased assets obtained in exchange for new finance lease liabilities	$ 55	$ 54