AmeriGas Merger and Acquisitions - Total Cash Paid and Liabilities Incurred (Details) $ in Millions	12 Months Ended
	Sep. 30, 2019 USD ($) mi	Sep. 30, 2018 USD ($) mi MW	Sep. 30, 2017 USD ($)
Business Acquisition [Line Items]
Natural gas lines, acquired (in miles) | mi	21	60
Payments to acquire long-term investments	$ 20.0	$ 70.3
Natural gas-fired peaking turbine, acquired (mw) | MW		44
UGI International
Business Acquisition [Line Items]
Total cash paid	49.3	$ 121.9	$ 99.7
Liabilities incurred	0.0	0.0	20.6
Total purchase price	49.3	121.9	120.3
Midstream & Marketing
Business Acquisition [Line Items]
Total cash paid	15.0
Liabilities incurred	0.0
Total purchase price	$ 15.0
AmeriGas Propane
Business Acquisition [Line Items]
Total cash paid		10.1	36.8
Liabilities incurred		2.7	10.8
Total purchase price		$ 12.8	$ 47.6