Contingent Liabilities and Commitments (Details) - Environmental assessment and remediation - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Site Contingency [Line Items]
Accrued environmental assessment and remediation costs, total	$ 1.1	$ 1.2
Accrued environmental assessment and remediation costs, current	0.1	0.1
Accrued environmental assessment and remediation costs, noncurrent	$ 1.0	$ 1.1