Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total Other items, net	$ 0.1	$ (5.1)	$ (0.7)	$ (5.1)
Interest expense	(39.1)	(47.2)	(86.4)	(94.0)
Cost of products sold	414.6	351.4	925.3	786.9
Loss / (earnings) before income taxes	(13.7)	21.9	73.6	80.6
Income tax (benefit)/expense	3.5	(8.2)	(16.7)	(21.1)
Net (loss)/earnings	(10.2)	(117.7)	56.9	(71.6)
Amount Reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net (loss)/earnings	5.2	1.5	10.5	2.0
Gains and losses on cash flow hedges | Amount Reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total Other items, net	3.4	(0.8)	6.0	(2.7)
Interest expense	(1.8)	0.6	3.1	1.1
Cost of products sold	(0.5)	0.0	0.3	0.3
Loss / (earnings) before income taxes	4.7	(0.2)	9.4	(1.3)
Income tax (benefit)/expense	1.2	0.1	(2.3)	0.3
Net (loss)/earnings	3.5	(0.1)	7.1	(1.0)
Amortization of defined benefit pension items | Amount Reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial loss	(2.2)	1.9	4.4	3.8
Income tax (benefit)/expense	0.5	(0.3)	(1.0)	(0.8)
Net (loss)/earnings	$ 1.7	$ 1.6	$ 3.4	$ 3.0