Acquisitions (Schedule of Pro Forma) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Business Acquisition [Line Items]
Net loss attributable to common stock per share – basic (in dollars per share)	$ (1.95)	$ (2.71)
Net loss attributable to common stock per share – diluted (in dollars per share)	$ (1.95)	$ (2.71)
Indigo Natural Resources, LLC and GEPH Merger
Business Acquisition [Line Items]
Revenues	$ 2,084	$ 5,031
Net loss attributable to common stock	$ (2,177)	$ (3,022)