Commitments and Contingencies (Details) $ in Millions	9 Months Ended
	Jun. 30, 2020 USD ($) Bcf
Commitments and Contingencies Disclosure [Abstract]
Self-insurance retention expense | $	$ 1.0
Short-term Contract with Customer | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term purchase commitment, minimum volume required	59.3
Long-term Contract with Customer Within Two To Three Years | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term purchase commitment, minimum volume required	71.5
Long-term Contract with Customer Beyond Three Years | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term purchase commitment, minimum volume required	0.2