Restructuring (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 30.8	$ 31.1	$ 25.3
Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.9	0.9	6.3
Selling, technical, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring charges	29.9	30.2	19.0
Performance Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	23.5	25.0	6.9
Expected restructuring costs remaining	0.0
Agricultural Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	7.3	$ 6.1	$ 18.4
Expected restructuring costs remaining	$ 0.0