Schedule of Accumulated Other Comprehensive Income (Loss) (Details) $ in Millions	9 Months Ended
Jun. 30, 2019 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2018	$ (241.8)
OCI before reclassifications	(2.8)
Reclassifications to earnings	(2.3)
Activity related to discontinued operations	1.6
Balance at June 30, 2019	(245.3)
Foreign Currency Translation Adjustments (1)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2018	(113.6)
OCI before reclassifications	3.3
Reclassifications to earnings	0.0
Activity related to discontinued operations	1.0
Balance at June 30, 2019	(109.3)
Pension Activity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2018	(136.4)
OCI before reclassifications	(0.2)
Reclassifications to earnings	3.2
Activity related to discontinued operations	0.0
Balance at June 30, 2019	(133.4)
Foreign Currency Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2018	3.3
OCI before reclassifications	2.9
Reclassifications to earnings	(5.2)
Activity related to discontinued operations	0.0
Balance at June 30, 2019	1.0
Zinc contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2018	0.0
OCI before reclassifications	(0.5)
Reclassifications to earnings	0.0
Activity related to discontinued operations	0.6
Balance at June 30, 2019	0.1
Interest Rate Contracts \| Foreign Currency Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at September 30, 2018	4.9
OCI before reclassifications	(8.3)
Reclassifications to earnings	(0.3)
Activity related to discontinued operations	0.0
Balance at June 30, 2019	$ (3.7)

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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