Leases - Supplemental Cash Flow and Other Information Related to Leases (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases	$ 141	$ 127
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from finance leases	6	6
Cash paid for amounts included in the measurement of lease liabilities: Financing cash flows from finance leases	5	7
Right-of-use assets obtained in exchange for new finance lease liabilities	22	2
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 119	$ 86