Acquisitions - Narrative (Details) - USD ($) $ in Millions			9 Months Ended
	Jan. 27, 2025	Jan. 17, 2025	Sep. 30, 2025
Avant
Business Combination [Line Items]
Asset acquisition, consideration transferred		$ 1,500
FME and Avant
Business Combination [Line Items]
Transaction cost			$ 15
Franklin Mountain Energy
Business Combination [Line Items]
Total consideration	$ 2,518
Cash consideration	$ 1,733
Total shares of Coterra common stock issued (in shares)	28,190,682
Total value of Coterra common stock issued	$ 785