Discontinued Operations - Discontinued Operations (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) parcelOfLand	Mar. 31, 2019 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operations, net of income taxes	$ (7.5)	$ 9.6
Adjustment for workers’ compensation, product liability, and other postretirement benefits, income tax benefit (expense)	0.1	(4.6)
Provision for environmental liabilities, income tax benefit (expense)	0.5	0.0
Provision for legal reserves and expenses, income tax benefit (expense)	2.0	1.0
Adjustment for workers’ compensation, product liability, other postretirement benefits and other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operations, net of income taxes	0.9	23.0
Provision for environmental liabilities, net of recoveries
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operations, net of income taxes	(1.9)	0.2
Provision for legal reserves and expenses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operations, net of income taxes	(7.5)	(3.6)
Discontinued operations of FMC Lithium
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operations, net of income taxes	1.0	(10.0)
Discontinued operations, income tax benefit (expense)	$ (0.2)	$ (4.7)
Newark Environmental Site
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Parcels of land | parcelOfLand	2
Gain on sale, net of tax	$ 21.0