Commitments and Contingencies (Details)	6 Months Ended
	Mar. 31, 2016 USD ($) subsidiary	Mar. 31, 2015 USD ($)
Environmental Issue
Commitments and Contingencies
Base year for determination of investigation and remediation cost (in years)	5 years
CPG and PNG COAs
Commitments and Contingencies
Accrual for environmental loss contingencies	$ 11,766,000	$ 9,610,000
CPG MGP | Environmental Issue
Commitments and Contingencies
Environmental expenditures cap during year	$ 1,800,000
PNG MGP
Commitments and Contingencies
Option to termination agreement by either party effective at end of any two-year period beginning with the original effective date in March 2004 (in years)	2 years
PNG MGP | Environmental Issue
Commitments and Contingencies
Environmental expenditures cap during year	$ 1,100,000
UGI Gas MGP Properties | Environmental Issue
Commitments and Contingencies
Expected environmental expenditures cap during year	2,500,000
UGI Gas-COA
Commitments and Contingencies
Accrual for environmental loss contingencies	$ 43,767,000
PNG and CPG
Commitments and Contingencies
Number of subsidiaries acquired with similar histories | subsidiary	2