Commitments and Contingencies (Details)	9 Months Ended
	Jun. 30, 2018 USD ($) subsidiary	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)
UGI Gas | Environmental Issue
Loss Contingencies [Line Items]
Environmental expenditures cap during year	$ 2,500,000
CPG MGP | Environmental Issue
Loss Contingencies [Line Items]
Environmental expenditures cap during year	1,750,000
PNG MGP | Environmental Issue
Loss Contingencies [Line Items]
Environmental expenditures cap during year	1,100,000
CPG, PNG and UGI Gas COAs
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 52,231,000	$ 54,250,000	$ 55,185,000
PNG and CPG
Loss Contingencies [Line Items]
Number of subsidiaries acquired with similar histories | subsidiary	2