Leases - Supplemental Cash Flow and Other Information Related to Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases	$ 56	$ 47
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from finance leases	1	2
Cash paid for amounts included in the measurement of lease liabilities: Financing cash flows from finance leases	1	1
Right-of-use assets obtained in exchange for new finance lease liabilities		17
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 26	$ 35