Discontinued Operations - Reserves for Discontinued Operations (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Workers' compensation, product liability, and indemnification reserves	$ 1.8	$ 2.2
Reserve for discontinued operations	71.9	72.2
Workers’ compensation, product liability, and indemnification reserves
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Workers' compensation, product liability, and indemnification reserves	15.7	23.6
Postretirement medical and life insurance benefits reserve, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Postretirement medical and life insurance benefits reserve, net	5.9	7.0
Reserves for legal proceedings
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reserves for legal proceedings	$ 50.3	$ 41.6