Commitments and Contingencies (Details) $ in Millions				1 Months Ended			3 Months Ended		9 Months Ended
	Jun. 30, 2018 entity mi	Mar. 31, 2016 USD ($) company	Mar. 13, 2013 company mi	Sep. 30, 2017 company mi	Sep. 30, 2016 mi	Mar. 31, 2016 USD ($) mi	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Feb. 29, 2020 company	Dec. 31, 2019 USD ($)
Schedule of Equity Method Investments [Line Items]
Accrued probable future environmental expenditures							$ 122.3		$ 122.3			$ 112.0
Expense related to environmental activities							15.8	$ 6.4	19.3	$ 10.4
Insurance recoveries									8.7	$ 4.0
Contamination of Passaic River Study Area
Schedule of Equity Method Investments [Line Items]
Loss Contingency, number of third-party companies assuming responsibility for development of RIFS | company			70
Calvert City
Schedule of Equity Method Investments [Line Items]
Number of companies negotiating Consent Decree | company											3
Accrued probable future environmental expenditures							$ 108.2		$ 108.2
Lower Passaic River | Contamination of Passaic River Study Area
Schedule of Equity Method Investments [Line Items]
Length of portion of river | mi	8		17	8	8	8
Total estimated cost of remedy		$ 1,400.0				$ 1,400.0
Number of companies receiving notice of potential liability | company		100
Number of companies receiving notice of process to allocate remedial costs | company				80
Number of entities named in suit | entity	100