Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Sep. 30, 2017	Mar. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowances for doubtful accounts	$ 44.6	$ 26.9	$ 34.7
Property, plant and equipment, accumulated depreciation and amortization	$ 3,141.2	$ 3,312.9	$ 3,221.9
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)	174,015,641	173,987,691	173,949,791