Revenue Recognition - Disaggregation of Revenue By Major Product Category (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 1,197.3	$ 1,014.3	$ 1,206.1	$ 1,192.1	$ 1,099.4	$ 923.6	$ 1,154.4	$ 1,107.9	$ 4,609.8	$ 4,285.3	$ 2,531.2
Insecticides
Disaggregation of Revenue [Line Items]
Revenue									2,773.6	2,476.5
Herbicides
Disaggregation of Revenue [Line Items]
Revenue									1,228.8	1,251.2
Fungicides
Disaggregation of Revenue [Line Items]
Revenue									271.4	268.7
Other
Disaggregation of Revenue [Line Items]
Revenue									$ 336.0	$ 288.9