Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowances for doubtful accounts	$ 43.4	$ 26.9	$ 33.0
Property, plant and equipment, accumulated depreciation and amortization	$ 3,131.0	$ 3,312.9	$ 3,337.5
UGI Common Stock, without par value, shares authorized (in shares)	450,000,000	450,000,000	450,000,000
UGI Common Stock, without par value, shares issued (in shares)	174,111,691	173,987,691	173,960,691