Shareowners' Equity (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes									$ 1,037.4	$ 943.1	$ 1,127.5
Income tax provision									(211.7)	(213.4)	(299.9)
Net income	$ 204.6	$ 216.9	$ 189.5	$ 214.7	$ 185.2	$ 191.0	$ 168.0	$ 185.5	825.7	729.7	827.6
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income									99.6	58.4	33.9
Pension and other postretirement benefit plan adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service credit									(9.8)	(14.0)	(17.2)
Amortization of net actuarial loss									155.2	126.8	123.2
Settlements									2.8	0.0	0.0
Pension and other postretirement benefit plan adjustments [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes									148.2	112.8	106.0
Income tax provision									(50.6)	(39.0)	(36.4)
Net income									97.6	73.8	69.6
Net unrealized gains (losses) on cash flow hedges, net of tax [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes									3.0	(19.1)	(36.2)
Income tax provision									(1.0)	3.7	0.5
Net income									2.0	(15.4)	(35.7)
Foreign Exchange Forward [Member] | Sales [Member] | Net unrealized gains (losses) on cash flow hedges, net of tax [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive income, net of tax									(0.3)	5.5	8.4
Foreign Exchange Forward [Member] | Cost of Sales [Member] | Net unrealized gains (losses) on cash flow hedges, net of tax [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive income, net of tax									2.8	(25.5)	(44.6)
Foreign Exchange Forward [Member] | Selling, General and Administrative Expenses [Member] | Net unrealized gains (losses) on cash flow hedges, net of tax [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive income, net of tax									$ 0.5	$ 0.9	$ 0.0