Utility Regulatory Assets and Liabilities and Regulatory Matters - Narrative (Details) - USD ($) $ in Millions											1 Months Ended	12 Months Ended
	Oct. 20, 2017	Jul. 01, 2017	Jan. 19, 2017	Jan. 01, 2017	Oct. 19, 2016	Oct. 14, 2016	Jun. 30, 2016	Apr. 01, 2016	Jan. 19, 2016	Apr. 01, 2015	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2016
Regulatory Assets [Line Items]
Associated increase to utility property, plant and equipment												$ 5,564.6			$ 5,346.4
UGI Utilities
Regulatory Assets [Line Items]
Capitalized project costs															5.8
Project costs expensed in prior periods													$ 5.4
UGI Utilities | Information Technology
Regulatory Assets [Line Items]
Associated increase to utility property, plant and equipment															2.7
Pennsylvania Public Utility Commission
Regulatory Assets [Line Items]
Maximum period since petition to file a general rate filing												5 years
DSIC, percent of amount billed to customers														0.00%
Pennsylvania Public Utility Commission | PNG
Regulatory Assets [Line Items]
Requested operating revenue increase			$ 21.7
DSIC, percent of amount billed to customers		7.50%								0.00%
Pennsylvania Public Utility Commission | PNG | Subsequent Event
Regulatory Assets [Line Items]
Approved operating revenue increase	$ 11.3
Pennsylvania Public Utility Commission | UGI Gas
Regulatory Assets [Line Items]
Approved operating revenue increase						$ 27.0
Pennsylvania Public Utility Commission | CPG
Regulatory Assets [Line Items]
DSIC, percent of amount billed to customers		7.50%						0.00%
Pennsylvania Public Utility Commission | UGI Utilities
Regulatory Assets [Line Items]
Requested operating revenue increase									$ 58.6
Amount of operating revenue increase							$ 27.0
Gas Utility
Regulatory Assets [Line Items]
Fair value of unrealized gains (losses)												$ 0.1			4.3
Deferred Project Costs | UGI Utilities
Regulatory Assets [Line Items]
Associated increase to utility regulatory assets															$ 3.1
Minimum
Regulatory Assets [Line Items]
Average remaining depreciable lives of the associated property												1 year
Maximum
Regulatory Assets [Line Items]
Average remaining depreciable lives of the associated property												65 years
Maximum | Pennsylvania Public Utility Commission
Regulatory Assets [Line Items]
DSIC, percent of amount billed to customers				5.00%							5.00%
Maximum | Pennsylvania Public Utility Commission | PNG
Regulatory Assets [Line Items]
DSIC, percent of amount billed to customers											10.00%
Maximum | Pennsylvania Public Utility Commission | CPG
Regulatory Assets [Line Items]
DSIC, percent of amount billed to customers											10.00%
Maximum | Postretirement benefit overcollections
Regulatory Assets [Line Items]
Regulatory liability, period overcollections will be refunded to customers					10 years
Maximum | Removal Costs, Net
Regulatory Assets [Line Items]
Regulatory asset, amortization period												5 years