Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period			$ 5,531
Other comprehensive income (loss) before reclassification adjustments	$ (29)	$ (52)	(51)	$ 11
Amounts reclassified from AOCI	7	5	13	10
Other comprehensive income (loss) attributable to UGI	(22)	(47)	(38)	21
Balance, end of period	6,210	4,828	6,210	4,828
Postretirement Benefit Plans
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(15)	(26)	(17)	(26)
Other comprehensive income (loss) before reclassification adjustments	0	0	0	0
Amounts reclassified from AOCI	1	1	3	1
Other comprehensive income (loss) attributable to UGI	1	1	3	1
Balance, end of period	(14)	(25)	(14)	(25)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(19)	(49)	(33)	(54)
Other comprehensive income (loss) before reclassification adjustments	24	4	34	4
Amounts reclassified from AOCI	6	4	10	9
Other comprehensive income (loss) attributable to UGI	30	8	44	13
Balance, end of period	11	(41)	11	(41)
Foreign Currency
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(122)	(4)	(90)	(67)
Other comprehensive income (loss) before reclassification adjustments	(53)	(56)	(85)	7
Amounts reclassified from AOCI	0	0	0	0
Other comprehensive income (loss) attributable to UGI	(53)	(56)	(85)	7
Balance, end of period	(175)	(60)	(175)	(60)
Total
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(156)	(79)	(140)	(147)
Balance, end of period	$ (178)	$ (126)	$ (178)	$ (126)