Inventories - Narrative (Details) - UGI Utilities $ in Millions	9 Months Ended
	Jun. 30, 2018 USD ($) storage_agreement Bcf	Sep. 30, 2017 USD ($) Bcf	Jun. 30, 2017 USD ($) Bcf
Inventory
Number of storage agreements | storage_agreement	5
Volume of gas storage inventories released under SCAAs with non-affiliates (in bcf) | Bcf	1.2	2.3	1.1
Carrying value of gas storage inventories released under SCAAs with non-affiliates | $	$ 2.7	$ 6.7	$ 3.5
Maximum
Inventory
SCAA contract term (in years)	3 years