Quarterly Results - Unaudited - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Captive Insurance Equity Affiliate [Member]
Quarterly Charges And Credits	$ 0.6	$ 0.5	$ 0.4	$ 0.3	$ (0.1)	$ 0.4	$ 1.0	$ 0.4
Currency Conversion [Member]
Quarterly Charges And Credits	(0.1)	0.7	(0.1)	0.2	0.1	0.5	0.1	0.2
Customer Settlement [Member]
Quarterly Charges And Credits			0.4
Customer Bankruptcy [Member]
Quarterly Charges And Credits	1.1
Restructuring Charges (Credits) [Member]
Quarterly Charges And Credits	2.6	24.0
Houghton Combination-related expenses [Member]
Quarterly Charges And Credits	12.2	15.1	5.5	5.4	5.1	3.8	4.5	6.1
Pension and postretirement benefit costs, non-service components [Member]
Quarterly Charges And Credits	0.5	0.5	$ 0.9	$ 0.9	0.6	0.6	0.6	$ 0.6
U.S. Tax Reform Charges [Member]
Quarterly Charges And Credits	5.3	0.4			8.1	1.1	$ 1.2
Sale Of Inventory [Member]
Quarterly Charges And Credits	1.5	$ 10.2
Insurance Insolvency Recovery [Member]
Quarterly Charges And Credits	$ 0.1				$ 0.1
Gain On Liquidation Of Inactive Legal Entity [Member]
Quarterly Charges And Credits						$ 0.4