Pension and Other Postretirement Benefits (Before Tax Amounts Unrecognized in Net Periodic Benefit Cost Included in AOCI) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 386	$ 360
Prior service credit	(114)	(159)
Pension Benefits | LOOP LLC and Explorer Pipeline
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	(11)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	19	192
Prior service credit	(224)	$ (246)
Other Benefits | LOOP LLC and Explorer Pipeline
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 1