Leases - Operating Lease Assets and Liabilities in the Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Leases [Abstract]
Right-of-use assets classified in Other noncurrent assets	$ 131	$ 125	$ 320
Current portion of lease liabilities classified in Other current liabilities	38	38
Long-term portion of lease liabilities classified in Other noncurrent liabilities and deferred credits	100	98
Total lease liabilities	$ 138	$ 136
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:DeferredCreditsAndOtherLiabilitiesNoncurrent	us-gaap:DeferredCreditsAndOtherLiabilitiesNoncurrent