Accumulated Other Comprehensive Loss - Reclassifications out of Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 120.8	$ 297.8
Income tax provision	(40.5)	(534.2)
Net Income (Loss) Attributable to Parent	80.3	(236.4)
Sales	1,642.3	1,586.6
Cost of sales	(903.6)	(886.4)
Selling, general and administrative expenses	(386.7)	(386.6)
Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Income (Loss) Attributable to Parent	12.5	24.1
Pension and other postretirement benefit plan adjustments [Member] | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	18.4	27.6
Income tax provision	(4.3)	(7.4)
Net Income (Loss) Attributable to Parent	14.1	20.2
Amortization of prior service credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(1.1)	(1.1)
Amortization of net actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	19.7	28.7
Settlements
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(0.2)	0.0
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(2.3)	5.2
Income tax provision	0.7	(1.3)
Net Income (Loss) Attributable to Parent	(1.6)	3.9
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest | Forward exchange contracts | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	0.4	(0.5)
Cost of sales	(3.2)	5.9
Selling, general and administrative expenses	$ 0.5	$ (0.2)