Commitments and Contingencies (Details) $ in Millions	12 Months Ended
	Sep. 30, 2023 USD ($) $ / Mcf MMcf	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Long Term Purchase Commitment [Line Items]
Purchases under contract | $	$ 182.0	$ 352.6	$ 149.4
Supply Commitment
Long Term Purchase Commitment [Line Items]
Contract term	1 year
Purchase commitment volume	20,600
Supply Commitment | Weighted Average
Long Term Purchase Commitment [Line Items]
Fixed price contracts (USD per Mcf) | $ / Mcf	2.80
Supply Commitment | Short-term Contract with Customer
Long Term Purchase Commitment [Line Items]
Contract term	1 year
Purchase commitment volume	65,500
Supply Commitment | Long-term Contract with Customer Within Two To Three Years
Long Term Purchase Commitment [Line Items]
Purchase commitment volume	72,300,000
Supply Commitment | Long-term Contract with Customer Within Two To Three Years | Minimum
Long Term Purchase Commitment [Line Items]
Contract term	2 years
Supply Commitment | Long-term Contract with Customer Within Two To Three Years | Maximum
Long Term Purchase Commitment [Line Items]
Contract term	3 years