SUPPLEMENTAL OIL AND GAS DISCLOSURES (Unaudited) - Principal Sources of Change In Discounted Future Net Cash Flows (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Extractive Industries [Abstract]
Sales, net of production costs	$ (4,158)	$ (3,479)	$ (4,056)
Net change in prices and production costs	3,651	(3,835)	(21,710)
Discoveries and improved recovery, net of related costs	2,273	1,153	1,953
Change in future development costs	(279)	309	705
Previously estimated development costs incurred during the period	719	986	1,991
Revision of quantities	(344)	(574)	(2,292)
Purchases of minerals in-place	9	8	22
Accretion of discount	952	1,313	3,642
Change in income taxes	(617)	1,070	7,264
Sales of minerals in-place	(809)	(52)	(5,240)
Change in production rates and other	626	567	(3,343)
Change in the discounted future net cash flows, Total	$ 2,023	$ (2,534)	$ (21,064)