Acquisitions (Schedule of Pro Forma) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Business Acquisition [Line Items]
Net loss attributable to common stock per share – basic (in dollars per share)	$ (0.79)	$ (0.76)
Net loss attributable to common stock per share – diluted (in dollars per share)	$ (0.79)	$ (0.76)
Indigo Natural Resources, LLC and GEPH Merger
Business Acquisition [Line Items]
Revenues	$ 1,476	$ 2,947
Net loss attributable to common stock	$ (875)	$ (845)