Equity and Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions		9 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	[1]	$ (1,069.2)	$ (695.3)
Other comprehensive loss before reclassifications	[1]	(275.3)	(13.7)
Amounts reclassified from accumulated other comprehensive loss	[1]	30.5	13.6
Net current period other comprehensive (loss) income	[1]	(244.8)	(0.1)
Reclassification of stranded tax effects	[1]	(73.4)
Balance at end of period	[1]	(1,387.4)	(695.4)
Accumulated Net Gain (Loss) from Designated or Quality Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		0.7	(0.2)
Other comprehensive loss before reclassifications		(10.1)
Amounts reclassified from accumulated other comprehensive loss		2.2
Net current period other comprehensive (loss) income		(7.9)
Balance at end of period		(7.2)	(0.2)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		(698.0)	(465.9)
Amounts reclassified from accumulated other comprehensive loss		28.3	13.6
Net current period other comprehensive (loss) income		28.3	13.6
Reclassification of stranded tax effects		(73.4)
Balance at end of period		(743.1)	(452.3)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		(371.9)	(229.2)
Other comprehensive loss before reclassifications		(265.2)	(13.7)
Net current period other comprehensive (loss) income		(265.2)	(13.7)
Balance at end of period		$ (637.1)	$ (242.9)

[1] All amounts are net of tax and noncontrolling interests.