Restructuring and Other Charges (Income) - Activity (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Severance and Employee Benefits	$ 0.0
Other Charges (Income)	3.5
Asset Disposal Charges	1.2
Total	4.7	$ 0.0
Restructuring Reserve [Roll Forward]
Restructuring Reserve, Beginning Balance	6.5		$ 6.5
Change in reserves	3.5
Cash payments	(4.6)
Other	(0.6)
Restructuring Reserve, Ending Balance	4.8
Environmental charges, net	2.6	2.3
European herbicide portfolio sale	(85.0)	0.0
Other items, net	0.0	6.0
Other charges (income), net	(82.4)	$ 8.3
DuPont Crop restructuring
Restructuring Cost and Reserve [Line Items]
Severance and Employee Benefits	0.0
Other Charges (Income)	0.0
Asset Disposal Charges	1.0
Total	1.0
Accelerated depreciation	1.0
Lithium Restructuring
Restructuring Cost and Reserve [Line Items]
Severance and Employee Benefits	0.0
Other Charges (Income)	1.9
Asset Disposal Charges	0.2
Total	2.1
Restructuring Reserve [Roll Forward]
Restructuring Reserve, Beginning Balance	3.0		3.0
Change in reserves	(1.9)
Cash payments	(0.2)
Other	(0.1)
Restructuring Reserve, Ending Balance	4.8
Other workforce related and facility shutdowns
Restructuring Cost and Reserve [Line Items]
Severance and Employee Benefits	0.0
Other Charges (Income)	1.6
Asset Disposal Charges	0.0
Total	1.6
Restructuring Reserve [Roll Forward]
Restructuring Reserve, Beginning Balance	2.3		2.3
Change in reserves	1.6
Cash payments	(3.2)
Other	(0.7)
Restructuring Reserve, Ending Balance	0.0
Cheminova Restructuring
Restructuring Reserve [Roll Forward]
Restructuring Reserve, Beginning Balance	1.2		1.2
Change in reserves	0.0
Cash payments	(1.2)
Other	0.0
Restructuring Reserve, Ending Balance	$ 0.0
Scenario, Forecast | DuPont Crop restructuring
Restructuring Cost and Reserve [Line Items]
Accelerated depreciation			$ 15.0