Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	$ 4,394
Other comprehensive income before reclassification adjustments	34	$ 154
Amounts reclassified from AOCI	(10)	(5)
Other comprehensive (loss) income attributable to UGI	24	149
Balance, end of period	4,432	5,188
Total
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(256)	(380)
Balance, end of period	(232)	(231)
Postretirement Benefit Plans
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	17	14
Other comprehensive income before reclassification adjustments	0	0
Amounts reclassified from AOCI	0	0
Other comprehensive (loss) income attributable to UGI	0	0
Balance, end of period	17	14
Derivative Instruments
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	26	37
Other comprehensive income before reclassification adjustments	(15)	3
Amounts reclassified from AOCI	(10)	(5)
Other comprehensive (loss) income attributable to UGI	(25)	(2)
Balance, end of period	1	35
Foreign Currency
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(299)	(431)
Other comprehensive income before reclassification adjustments	49	151
Amounts reclassified from AOCI	0	0
Other comprehensive (loss) income attributable to UGI	49	151
Balance, end of period	$ (250)	$ (280)