Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Intangible assets subject to amortization (finite life)
Gross	$ 1,220.2	$ 1,228.1
Accumulated Amortization	(229.3)	(169.3)
Net	990.9	1,058.8
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	1,638.1	1,644.6
Finite and Indefinite lived intangible assets, gross	2,858.3	2,872.7
Total Accumulated Amortization	(229.3)	(169.3)
Total intangible assets	2,629.0	2,703.4
Crop Protection Brands
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	1,259.1	1,259.1
Brands
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	379.0	384.8
In-process research and development
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 0.0	0.7
Customer relationships
Intangible assets subject to amortization (finite life)
Weighted avg. useful life at December 31, 2019	17 years
Gross	$ 1,139.7	1,146.2
Accumulated Amortization	(184.7)	(128.7)
Net	955.0	1,017.5
Indefinite-lived Intangible Assets [Line Items]
Total Accumulated Amortization	$ (184.7)	(128.7)
Patents
Intangible assets subject to amortization (finite life)
Weighted avg. useful life at December 31, 2019	6 years
Gross	$ 1.7	1.7
Accumulated Amortization	(0.9)	(0.8)
Net	0.8	0.9
Indefinite-lived Intangible Assets [Line Items]
Total Accumulated Amortization	$ (0.9)	(0.8)
Brands
Intangible assets subject to amortization (finite life)
Weighted avg. useful life at December 31, 2019	8 years
Gross	$ 16.7	17.0
Accumulated Amortization	(6.7)	(5.9)
Net	10.0	11.1
Indefinite-lived Intangible Assets [Line Items]
Total Accumulated Amortization	$ (6.7)	(5.9)
Purchased and licensed technologies
Intangible assets subject to amortization (finite life)
Weighted avg. useful life at December 31, 2019	10 years
Gross	$ 60.2	61.3
Accumulated Amortization	(35.2)	(32.1)
Net	25.0	29.2
Indefinite-lived Intangible Assets [Line Items]
Total Accumulated Amortization	$ (35.2)	(32.1)
In-process research and development
Intangible assets subject to amortization (finite life)
Weighted avg. useful life at December 31, 2019	1 year
Gross	$ 1.9	1.9
Accumulated Amortization	(1.8)	(1.8)
Net	0.1	0.1
Indefinite-lived Intangible Assets [Line Items]
Total Accumulated Amortization	$ (1.8)	$ (1.8)