Properties and Equipment - Carried at Cost (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Properties and equipment-gross, at cost		$ 11,244	$ 9,949
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		3,654	2,683
Properties and equipment-net		7,590	7,266
Proved properties
Property, Plant and Equipment [Line Items]
Properties and equipment-gross, at cost	[1],[2]	8,719	7,289
Unproved Properties
Property, Plant and Equipment [Line Items]
Properties and equipment-gross, at cost	[1],[3]	1,765	1,891
Gathering, Processing and Other Facilities
Property, Plant and Equipment [Line Items]
Properties and equipment-gross, at cost	[1]	$ 403	294
Gathering, Processing and Other Facilities | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (years)	[1]	15 years
Gathering, Processing and Other Facilities | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (years)	[1]	25 years
Construction in Progress
Property, Plant and Equipment [Line Items]
Properties and equipment-gross, at cost	[1],[3]	$ 224	350
Other
Property, Plant and Equipment [Line Items]
Properties and equipment-gross, at cost	[1]	$ 133	$ 125
Other | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (years)	[1]	3 years
Other | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (years)	[1]	40 years

[1] Estimated useful lives are presented as of December 31, 2019.

[2] Proved properties are depreciated, depleted and amortized using the units-of-production method (see Note 1).

[3] Unproved properties, land and construction in progress are not subject to depreciation and depletion.