Contingent Liabilities and Commitments (Details) - Environmental assessment and remediation [Member] - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Site Contingency [Line Items]
Accrued environmental assessment and remediation costs, total	$ 1.1	$ 1.1
Accrued environmental assessment and remediation costs, current	0.2	0.1
Accrued environmental assessment and remediation costs, noncurrent	$ 0.9	$ 1.0