Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	$ 5,531
Other comprehensive income (loss) before reclassification adjustments	(22)	$ 63
Amounts reclassified from AOCI	6	5
Other comprehensive income (loss) attributable to UGI	(16)	68
Balance, end of period	5,359	4,446
Postretirement Benefit Plans
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(17)	(26)
Other comprehensive income (loss) before reclassification adjustments	0	0
Amounts reclassified from AOCI	2	0
Other comprehensive income (loss) attributable to UGI	2	0
Balance, end of period	(15)	(26)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(33)	(54)
Other comprehensive income (loss) before reclassification adjustments	10	0
Amounts reclassified from AOCI	4	5
Other comprehensive income (loss) attributable to UGI	14	5
Balance, end of period	(19)	(49)
Foreign Currency
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(90)	(67)
Other comprehensive income (loss) before reclassification adjustments	(32)	63
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss) attributable to UGI	(32)	63
Balance, end of period	(122)	(4)
Total
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(140)	(147)
Balance, end of period	$ (156)	$ (79)