Summary of Significant Accounting Policies - Principles of Consolidation (Details)	12 Months Ended
Sep. 30, 2020
Accounting Policies [Abstract]
Ownership interests in certain subsidiaries under equity method investment, maximum	100.00%

Ownership interests in certain subsidiaries under equity method investment, maximum

No definition available.

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Namespace Prefix:	ugi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration