Supplementary Information On Natural Gas, Oil And NGL Reserves (Summary of Proved Undeveloped Reserves) (Details) - 12 months ended Sep. 30, 2021	Bcfe	Mcfe
Extractive Industries [Abstract]
Beginning proved undeveloped reserves		3,060,656
Proved undeveloped reserves transferred to proved developed	(2.1)	(2,060,368)
Revisions		(629,317)
Extensions and discoveries		246,993
Purchases		4,645,269
Ending proved undeveloped reserves		5,263,233