Income Taxes - Deferred Tax Assets (Liabilities) Table (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred tax liabilities
Oil and gas exploration and development operations	$ (2,599)	$ (5,025)
Midstream and other depreciable properties	(543)	(870)
Mineral operations	(312)	(550)
Other	(54)	(147)
Gross long-term deferred tax liabilities	(3,508)	(6,592)
Deferred tax assets
Oil and gas exploration and development costs	309	250
Foreign and state net operating loss carryforwards	562	648
U.S. foreign tax credit carryforwards	2,685	1,834
Compensation and benefit plans	365	672
Mark to market on derivatives	232	324
Other	166	309
Gross long-term deferred tax assets	4,319	4,037
Valuation allowances on deferred tax assets not expected to be realized	(3,024)	(1,755)	$ (1,403)	$ (864)
Net long-term deferred tax assets	1,295	2,282
Total deferred taxes	$ (2,213)	$ (4,310)