Acquisitions and Divestitures - Additional Information - 2014 Activity - Anadarko Basin and Southern Louisiana Divestitures (Detail)	1 Months Ended	12 Months Ended
	Dec. 31, 2014 USD ($) a	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)		Dec. 31, 2014 USD ($) a
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of oil and gas assets		$ 134,000,000	$ 268,000,000	[1]	$ 470,000,000	[1]
Loss on sale of oil and gas property		(21,000,000)	(135,000,000)		216,000,000
Goodwill impairment charges		$ 0	$ 163,000,000		$ 347,000,000
Anadarko Basin and Southern Louisiana [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of oil and gas assets	$ 1,300,000,000
Anadarko Basin [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Oil and gas properties sold | a	115,000				115,000
Loss on sale of oil and gas property	$ 823,000,000
Goodwill impairment charges	10,000,000
Loss on disposal of assets, before tax	$ 180,000,000
Southern Louisiana [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Oil and gas properties sold | a	90,000				90,000

[1] Financial information for 2015 and 2014 has been recast to reflect retrospective application of the successful efforts method of accounting. See Note 1.