Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jul. 31, 2020
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 631	$ 648
Income Taxes Paid, Net	1	0
Non-cash investing and financing activities
Net transfers of property, plant and equipment (to)/from materials and supplies inventories	$ (1)	$ 1
Western Refining Wholesale & Western Refining Product Transport [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Partner Capital, Units, contributed, fair value assigned			$ 340