THE ACQUISITION - PRO FORMA INFORMATION (Details) - Anadarko Petroleum Corporation - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Revenues	$ 28,723	$ 31,206
Net income (loss) attributable to common stockholders	$ (769)	$ 2,965
Net income (loss) attributable to common stockholders per share—basic (usd per share)	$ (0.95)	$ 3.26
Net income (loss) attributable to common stockholders per share—diluted (usd per share)	$ (0.95)	$ 3.25
Net income (loss) attributable to common stockholders excluding pro-forma results of WES	$ (1,100)	$ 2,800