Supplemental Cash Flow Information - Summary of Cash Paid (Received) for Interest and Income Taxes and Non-cash Investing and Financing Activities (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash paid (received)
Interest, net of amounts capitalized	$ 536	$ 471
Income taxes, net of refunds	29	53
Non-cash investing activities
Fair value of properties and equipment acquired	1	7
Asset retirement cost additions	117	162
Accruals of property, plant, and equipment	748	1,036
Net liabilities assumed (divested) in acquisitions and divestitures	0	(97)
Non-cash investing and financing activities
Finance leases	22	0
Settlement of Tangible Equity Units	$ 0	$ 300