Impairments - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Property, Plant, and Equipment [Line Items]
Impairment of unproved properties		$ 300	$ 1,993
Net book value		$ 31,099		$ 33,751
Percent decline in oil price assumption for impairment analysis		10.00%
Percent decline in natural-gas price assumption for impairment analysis		10.00%
Unproved Utica Properties [Member]
Property, Plant, and Equipment [Line Items]
Impairment of unproved properties	$ 109
Unproved Greater Natural Buttes Properties [Member]
Property, Plant, and Equipment [Line Items]
Impairment of unproved properties			$ 935
Certain International Asset Group at Risk for Impairment [Member]
Property, Plant, and Equipment [Line Items]
Net book value		$ 1,400
Potential non-cash impairments that could be recognized in the future, in excess of		600
Certain U.S. Onshore Asset Groups at Risk for Impairment [Member]
Property, Plant, and Equipment [Line Items]
Net book value		1,100
Potential non-cash impairments that could be recognized in the future, in excess of		$ 400