Schedule of Accumulated Other Comprehensive Income (Loss) (Details) $ in Millions	3 Months Ended
	Dec. 31, 2020 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2020	$ (307.7)
OCI before reclassifications	(2.9)
Reclassifications to earnings	5.3
Balance at December 31, 2020	(305.3)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2020	(137.4)
OCI before reclassifications	5.5
Reclassifications to earnings	0.0
Balance at December 31, 2020	(131.9)
Pension Activity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2020	(163.5)
OCI before reclassifications	(2.2)
Reclassifications to earnings	1.7
Balance at December 31, 2020	(164.0)
Foreign Currency Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2020	(4.1)
OCI before reclassifications	(5.9)
Reclassifications to earnings	2.0
Balance at December 31, 2020	(8.0)
Zinc contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2020	3.4
OCI before reclassifications	3.4
Reclassifications to earnings	0.6
Balance at December 31, 2020	7.4
Interest Rate Contracts | Foreign Currency Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2020	(6.1)
OCI before reclassifications	(3.7)
Reclassifications to earnings	1.0
Balance at December 31, 2020	$ (8.8)