Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
AOCI Including Portion Attributable to NCI [Roll Forward]:
Balance, beginning of year	$ 6,074	$ 5,531
Other comprehensive income (loss) before reclassification adjustments	153	(249)	$ (13)
Amounts reclassified from AOCI	(29)	9	20
Other comprehensive income (loss) attributable to UGI	124	(240)	7
Balance, end of year	4,394	6,074	5,531
Accumulated other comprehensive income (loss)
AOCI Including Portion Attributable to NCI [Roll Forward]:
Balance, beginning of year	(380)	(140)	(147)
Balance, end of year	(256)	(380)	(140)
Postretirement Benefit Plans
AOCI Including Portion Attributable to NCI [Roll Forward]:
Balance, beginning of year	14	(17)	(26)
Other comprehensive income (loss) before reclassification adjustments	5	28	7
Amounts reclassified from AOCI	(2)	3	2
Other comprehensive income (loss) attributable to UGI	3	31	9
Balance, end of year	17	14	(17)
Derivative Instruments
AOCI Including Portion Attributable to NCI [Roll Forward]:
Balance, beginning of year	37	(33)	(54)
Other comprehensive income (loss) before reclassification adjustments	16	64	3
Amounts reclassified from AOCI	(27)	6	18
Other comprehensive income (loss) attributable to UGI	(11)	70	21
Balance, end of year	26	37	(33)
Foreign Currency
AOCI Including Portion Attributable to NCI [Roll Forward]:
Balance, beginning of year	(431)	(90)	(67)
Other comprehensive income (loss) before reclassification adjustments	132	(341)	(23)
Amounts reclassified from AOCI	0	0	0
Other comprehensive income (loss) attributable to UGI	132	(341)	(23)
Balance, end of year	$ (299)	$ (431)	$ (90)