Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Loss	Treasury Stock at Cost	Retained Earnings	Non- controlling Interests
Balance at Beginning of Period at Dec. 31, 2016	$ 9,600	$ 5	$ 6,450	$ (31)	$ (692)	$ 3,556	$ 312
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	(1,566)					(1,612)	46
Clayton Williams Energy Acquisition	1,851		1,876		(25)
Stock-based Compensation	80		80
Dividends	(141)					(141)
Issuance of Noble Midstream Partners Common Units, Net of Offering Costs	138						138
Distributions to Noncontrolling Interest Owners	(19)						(19)
Other	0		9	2	(11)
Balance at End of Period at Sep. 30, 2017	9,943	5	8,415	(29)	(728)	1,803	477
Balance at Beginning of Period at Dec. 31, 2017	10,619	5	8,438	(30)	(725)	2,248	683
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	816					758	58
Stock-based Compensation	63		63
Dividends	(156)					(156)
Purchase and Retirement of Common Stock	(233)		(233)
Clayton Williams Energy Acquisition	(25)		(25)
Contributions from Noncontrolling Interest Owners	348						348
Distributions to Noncontrolling Interest Owners	(35)						(35)
Other	(3)			3	(6)
Balance at End of Period at Sep. 30, 2018	$ 11,394	$ 5	$ 8,249	$ (27)	$ (731)	$ 2,850	$ 1,048