Commitments and Contingencies (Details) $ in Millions	9 Months Ended
	Jun. 30, 2019 USD ($) Bcf
Loss Contingencies [Line Items]
Self-insurance retention expense | $	$ 1.0
Operating Leased Assets [Line Items]
Operating leases, future minimum payments due | $	$ 194.9
Minimum
Operating Leased Assets [Line Items]
Lease term of contract	1 year
Maximum
Operating Leased Assets [Line Items]
Lease term of contract	20 years
Long-term Contract with Customer | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Minimum Volume Required | Bcf	1,800
Short-term Contract with Customer | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Minimum Volume Required | Bcf	53,900