Leases - Balance Sheet Classification and Other Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019		Jan. 01, 2019
Balance Sheet Classification
Right-of-use asset	$ 472	$ 532	[1]	$ 534
Current lease liabilities (recorded in other current liabilities)	45	57
Long-term lease liabilities	455	493	[1]
Total operating lease liabilities	$ 500	$ 550
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherCurrentLiabilitiesMember	us-gaap:OtherCurrentLiabilitiesMember
Other Information
Weighted-average remaining lease term for operating leases	35 years	33 years
Weighted-average discount rate for operating leases	5.00%	5.00%

[1] Certain prior year data has been reclassified to conform to the current presentation.