Acquisitions (Schedule of Pro Forma) (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) $ / shares
Business Acquisition [Line Items]
Net income (loss) attributable to common stock per share – basic (in dollars per share) | $ / shares	$ 0.03
Net income (loss) attributable to common stock per share – diluted (in dollars per share) | $ / shares	$ 0.03
Montage Resources Corporation and Indigo Natural Resources, LLC
Business Acquisition [Line Items]
Revenues | $	$ 1,471
Net income attributable to common stock | $	$ 30