Consolidated Statements of Shareholders' 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, 2017	$ 10,619	$ 5	$ 8,438	$ (30)	$ (725)	$ 2,248	$ 683
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss) Income	574					554	20
Stock-based Compensation	17		17
Dividends	(48)					(48)
Purchase and Retirement of Common Stock	(67)		(67)
Clayton Williams Energy Acquisition	(25)		(25)
Distributions to Noncontrolling Interest Owners	(11)						(11)
Contributions from Noncontrolling Interest Owners	331						331
Other	(3)			1	(6)		2
Balance at End of Period at Mar. 31, 2018	11,387	5	8,363	(29)	(731)	2,754	1,025
Balance at Beginning of Period at Dec. 31, 2018	10,484	5	8,203	(32)	(730)	1,980	1,058
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss) Income	(289)					(313)	24
Stock-based Compensation	14		14
Dividends	(53)					(53)
Distributions to Noncontrolling Interest Owners	(17)						(17)
Contributions from Noncontrolling Interest Owners	10						10
Other	(6)		2		(5)		(3)
Balance at End of Period at Mar. 31, 2019	$ 10,143	$ 5	$ 8,219	$ (32)	$ (735)	$ 1,614	$ 1,072