Summary of Significant Accounting Policies - Refundable Tank and Cylinder Deposits (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Accounting Policies [Abstract]
Customer paid deposits primarily on owned tanks and cylinders	$ 296	$ 300

Foreign subsidiary tank and cylinder customer deposits.

No definition available.

Name:	ugi_ForeignSubsidiaryCustomerDeposits
Namespace Prefix:	ugi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant