Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period			$ 4,100.0
Other comprehensive income (loss) before reclassification adjustments (after-tax)	$ 14.5	$ (78.3)	(30.6)	$ (22.1)
Amounts reclassified from AOCI:
Reclassification adjustments (pre-tax)	1.2	1.2	3.0	6.0
Reclassification adjustments tax benefit	(0.3)	(0.4)	(0.8)	(2.1)
Reclassification adjustments (after-tax)	0.9	0.8	2.2	3.9
Other comprehensive income (loss) attributable to UGI	15.4	(77.5)	(28.4)	(18.2)
Reclassification of stranded income tax effects related to TCJA			(6.6)
Balance, end of period	4,173.7	4,227.8	4,173.7	4,227.8
Postretirement Benefit Plans
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(13.3)	(18.5)	(11.0)	(19.2)
Other comprehensive income (loss) before reclassification adjustments (after-tax)	0.0	0.0	0.0	0.0
Amounts reclassified from AOCI:
Reclassification adjustments (pre-tax)	0.3	0.8	1.1	1.8
Reclassification adjustments tax benefit	(0.1)	(0.2)	(0.3)	(0.5)
Reclassification adjustments (after-tax)	0.2	0.6	0.8	1.3
Other comprehensive income (loss) attributable to UGI	0.2	0.6	0.8	1.3
Reclassification of stranded income tax effects related to TCJA			(2.9)
Balance, end of period	(13.1)	(17.9)	(13.1)	(17.9)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(21.8)	(21.0)	(16.1)	(21.4)
Other comprehensive income (loss) before reclassification adjustments (after-tax)	(1.6)	3.7	(4.3)	1.7
Amounts reclassified from AOCI:
Reclassification adjustments (pre-tax)	0.9	0.4	1.9	4.2
Reclassification adjustments tax benefit	(0.2)	(0.2)	(0.5)	(1.6)
Reclassification adjustments (after-tax)	0.7	0.2	1.4	2.6
Other comprehensive income (loss) attributable to UGI	(0.9)	3.9	(2.9)	4.3
Reclassification of stranded income tax effects related to TCJA			(3.7)
Balance, end of period	(22.7)	(17.1)	(22.7)	(17.1)
Foreign Currency
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(125.7)	5.4	(83.3)	(52.8)
Other comprehensive income (loss) before reclassification adjustments (after-tax)	16.1	(82.0)	(26.3)	(23.8)
Amounts reclassified from AOCI:
Reclassification adjustments (pre-tax)	0.0	0.0	0.0	0.0
Reclassification adjustments tax benefit	0.0	0.0	0.0	0.0
Reclassification adjustments (after-tax)	0.0	0.0	0.0	0.0
Other comprehensive income (loss) attributable to UGI	16.1	(82.0)	(26.3)	(23.8)
Reclassification of stranded income tax effects related to TCJA			0.0
Balance, end of period	(109.6)	(76.6)	(109.6)	(76.6)
Total
AOCI Attributable to Parent, Net of Tax
Balance, beginning of period	(160.8)	(34.1)	(110.4)	(93.4)
Amounts reclassified from AOCI:
Balance, end of period	$ (145.4)	$ (111.6)	$ (145.4)	$ (111.6)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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