Other Comprehensive Income (Schedule of Items Reclassified out of AOCL) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net									$ 7.5
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									(2.2)	$ (4.2)	$ (2.0)
Other Comprehensive Income (Loss), before Reclassifications, before Tax									(5.1)	(66.9)	4.9
Tax effect									48.2	56.4	(55.2)
Net of tax	$ (42.4)	$ (93.9)	$ (46.9)	$ (39.8)	$ (27.9)	$ (32.6)	$ (49.5)	$ (42.2)	(223.0)	$ (152.2)	(252.4)
Accounting Standards Update 2018-02
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Description of Prior-period Information Retrospectively Adjusted										—
Retained Earnings [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax									(223.0)	$ (152.2)	(252.4)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax										$ (4.8)
New Accounting Pronouncement or Change in Accounting Principle, Description of Prior-period Information Retrospectively Adjusted										0.8
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									0.0	$ 0.0	0.0
Other Comprehensive Income (Loss), before Reclassifications, before Tax									34.7	(40.1)	(24.0)
Change in Pension and Postretirement Defined Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									(4.6)	(2.0)	(3.0)
Other Comprehensive Income (Loss), before Reclassifications, before Tax									0.9	$ (19.4)	7.9
New Accounting Pronouncement or Change in Accounting Principle, Description of Prior-period Information Retrospectively Adjusted										(6.2)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									6.8	$ 6.2	5.0
Other Comprehensive Income (Loss), before Reclassifications, before Tax									(40.7)	$ (7.4)	21.0
Tax effect									1.5		1.2
AOCI Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Description of Prior-period Information Retrospectively Adjusted										(5.4)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax effect										$ 1.4
Reclassification out of Accumulated Other Comprehensive Income [Member] | Change in Pension and Postretirement Defined Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax effect									(1.4)	(2.4)	(1.0)
Net of tax									(3.2)	0.4	(2.0)
Foreign Exchange Forward [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax effect										(0.2)
Net of tax										0.4
Interest Rate Swap [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax effect										1.6
Net of tax									(5.3)	$ 5.2	(3.8)
New Accounting Pronouncement or Change in Accounting Principle, Description of Prior-period Information Retrospectively Adjusted										0.8
Interest Rate Swap [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									4.2	$ 6.8	5.3
Other Comprehensive Income (Loss), before Reclassifications, before Tax									(35.4)	(24.8)	22.8
Tax effect									1.0		1.2
Net of tax									3.2		4.1
Foreign Exchange | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									2.6	(0.6)	(0.3)
Other Comprehensive Income (Loss), before Reclassifications, before Tax									1.9	$ (0.6)	0.4
Tax effect									0.5		0.0
Net of tax									$ 2.1		$ (0.3)