Hedging Activities, Derivative Instruments and Fair Value Measurements - Fair Value Measurements (Details) - Recurring - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Financial Assets
Foreign currency forwards	$ 0.1	$ 2.9
Trading securities held in deferred compensation plan	11.4	9.1
Total	11.5	12.0
Financial Liabilities
Foreign currency forwards	0.1	0.7
Deferred compensation plans	24.8	25.7
Total	24.9	26.4
Level 1
Financial Assets
Foreign currency forwards	0.0	0.0
Trading securities held in deferred compensation plan	11.4	9.1
Total	11.4	9.1
Financial Liabilities
Foreign currency forwards	0.0	0.0
Deferred compensation plans	24.8	25.7
Total	24.8	25.7
Level 2
Financial Assets
Foreign currency forwards	0.1	2.9
Trading securities held in deferred compensation plan	0.0	0.0
Total	0.1	2.9
Financial Liabilities
Foreign currency forwards	0.1	0.7
Deferred compensation plans	0.0	0.0
Total	0.1	0.7
Level 3
Financial Assets
Foreign currency forwards	0.0	0.0
Trading securities held in deferred compensation plan	0.0	0.0
Total	0.0	0.0
Financial Liabilities
Foreign currency forwards	0.0	0.0
Deferred compensation plans	0.0	0.0
Total	$ 0.0	$ 0.0