Restructuring - Rollforward of all restructuring accrual (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Rollforward of all restructuring accrual
Balance at beginning of period	$ 3.9	$ 2.4	$ 5.3	$ 2.0
Restructuring (income) expense	0.0	0.2	(0.1)	1.7
Use of reserve	(0.8)	(0.7)	(2.3)	(1.8)
Currency translation			0.2
Balance at end of period	$ 3.1	$ 1.9	$ 3.1	$ 1.9