Quarterly Results - Unaudited - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Captive Insurance Equity Affiliate [Member]
Quarterly Charges And Credits	$ 0.1	$ 0.4	$ 1.0	$ 0.4	$ 1.1	$ 0.4	$ 0.4	$ 0.6
Currency Conversion [Member]
Quarterly Charges And Credits	0.1	0.5	0.1	0.2	0.1	0.1	0.3
Cost Streamlining Initiative [Member]
Quarterly Charges And Credits								0.3
Houghton Combination-related expenses [Member]
Quarterly Charges And Credits	5.1	3.8	4.5	$ 6.1	7.7	$ 9.7	4.3	$ 9.1
U.S. Pension Plan Settlement Charge [Member]
Quarterly Charges And Credits							$ 1.9
U.S. Tax Reform Charges [Member]
Quarterly Charges And Credits	8.1	1.1	$ 1.2		22.2
Loss On Disposal Of Held For Sale Asset [Member]
Quarterly Charges And Credits					0.1
Insurance Insolvency Recovery [Member]
Quarterly Charges And Credits	$ 0.1				$ 0.6
Gain On Liquidation Of Inactive Legal Entity [Member]
Quarterly Charges And Credits		$ 0.4