Commitments and Contingencies (Details)	5 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($) lb	Sep. 30, 2015 USD ($) lawsuit	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)
Commitments and Contingencies
Aggregate rental expense for leases		$ 86,100,000	$ 79,700,000	$ 82,500,000
Accrued liabilities for environmental investigation and remediation costs related to CPG-COA and PNG-COA	$ 13,800,000	$ 13,800,000	$ 10,700,000
Class action lawsuits (more than 35) | lawsuit		35
Amount of propane in cylinders being sold | lb	17
Reduced amount of propane in cylinders being sold | lb	15
PNG MGP
Commitments and Contingencies
Loss contingency, settlement agreement, terms		2 years
Environmental Issue
Commitments and Contingencies
Base year for determination of investigation and remediation cost (in years)		5 years
Environmental Issue | CPG MGP
Commitments and Contingencies
Environmental expenditures cap during calendar year		$ 1,800,000
Environmental Issue | PNG MGP
Commitments and Contingencies
Environmental expenditures cap during calendar year		$ 1,100,000
Maximum | Gas Utility
Commitments and Contingencies
Term of contracts		16 months
Maximum | Midstream and Marketing
Commitments and Contingencies
Term of contracts		2 years
Maximum | Partnership
Commitments and Contingencies
Term of contracts		3 years
Maximum | UGI International
Commitments and Contingencies
Term of contracts		3 years
The Partnership and UGI International | Minimum
Commitments and Contingencies
Contract terms subject to annual price and quantity adjustments (in years)		1 year
The Partnership and UGI International | Maximum
Commitments and Contingencies
Contract terms subject to annual price and quantity adjustments (in years)		3 years