Accumulated Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Mar. 31, 2016	Mar. 31, 2015		Mar. 31, 2016	Mar. 31, 2015
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period					$ 3,572.4
Amounts reclassified from AOCI:
Other comprehensive income (loss)		$ 13.0	$ (45.8)		(15.3)	$ (65.9)
Balance, end of period		3,925.0	3,883.7		3,925.0	3,883.7
Postretirement Benefit Plans
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period		(20.0)	(20.0)		(20.4)	(20.6)
Other comprehensive (loss) income before reclassification adjustments (after-tax)		0.0	0.0		0.0	0.0
Amounts reclassified from AOCI:
Reclassification adjustments (pre-tax)		0.4	0.6		1.1	1.6
Reclassification adjustments tax benefit (expense)		(0.1)	(0.2)		(0.4)	(0.6)
Reclassification adjustments (after-tax)		0.3	0.4		0.7	1.0
Other comprehensive income (loss)			0.4			1.0
Add other comprehensive loss attributable to noncontrolling interests, principally in AmeriGas Partners			0.0			0.0
Other comprehensive income (loss) attributable to UGI		0.3	0.4		0.7	1.0
Balance, end of period		(19.7)	(19.6)		(19.7)	(19.6)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period		12.7	1.7		11.2	(9.3)
Other comprehensive (loss) income before reclassification adjustments (after-tax)		(29.7)	20.2		(22.9)	27.9
Amounts reclassified from AOCI:
Reclassification adjustments (pre-tax)		(7.0)	(3.0)		(15.5)	0.6
Reclassification adjustments tax benefit (expense)		2.7	1.1		5.9	(0.4)
Reclassification adjustments (after-tax)		(4.3)	(1.9)		(9.6)	0.2
Other comprehensive income (loss)			18.3			28.1
Add other comprehensive loss attributable to noncontrolling interests, principally in AmeriGas Partners			0.5			1.7
Other comprehensive income (loss) attributable to UGI		(34.0)	18.8		(32.5)	29.8
Balance, end of period		(21.3)	20.5		(21.3)	20.5
Foreign Currency
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period		(135.6)	(21.8)	[1]	(105.4)	8.7	[1]
Other comprehensive (loss) income before reclassification adjustments (after-tax)		46.7	(64.5)	[1]	16.5	(95.0)	[1]
Amounts reclassified from AOCI:
Reclassification adjustments (pre-tax)		0.0	0.0	[1]	0.0	0.0	[1]
Reclassification adjustments tax benefit (expense)		0.0	0.0	[1]	0.0	0.0	[1]
Reclassification adjustments (after-tax)		0.0	0.0	[1]	0.0	0.0	[1]
Other comprehensive income (loss)	[1]		(64.5)			(95.0)
Add other comprehensive loss attributable to noncontrolling interests, principally in AmeriGas Partners	[1]		0.0			0.0
Other comprehensive income (loss) attributable to UGI		46.7	(64.5)	[1]	16.5	(95.0)	[1]
Balance, end of period		(88.9)	(86.3)	[1]	(88.9)	(86.3)	[1]
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period		(142.9)	(40.1)		(114.6)	(21.2)
Other comprehensive (loss) income before reclassification adjustments (after-tax)		17.0	(44.3)		(6.4)	(67.1)
Amounts reclassified from AOCI:
Reclassification adjustments (pre-tax)		(6.6)	(2.4)		(14.4)	2.2
Reclassification adjustments tax benefit (expense)		2.6	0.9		5.5	(1.0)
Reclassification adjustments (after-tax)		(4.0)	(1.5)		(8.9)	1.2
Other comprehensive income (loss)			(45.8)			(65.9)
Add other comprehensive loss attributable to noncontrolling interests, principally in AmeriGas Partners			0.5			1.7
Other comprehensive income (loss) attributable to UGI		13.0	(45.3)		(15.3)	(64.2)
Balance, end of period		$ (129.9)	$ (85.4)		$ (129.9)	$ (85.4)

[1] See Note 2 relating to correction of prior period error in other comprehensive income.