Revenue Disaggregation of Revenue - Principal Product Groups (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Net Sales	$ 1,911	$ 3,396	$ 1,947	$ 10,863	$ 11,472
Seed [Member]
Disaggregation of Revenue [Line Items]
Net Sales	681		551	6,347	6,716
Seed [Member] | Corn [Member]
Disaggregation of Revenue [Line Items]
Net Sales	372		344	4,149	4,289
Seed [Member] | Soybean [Member]
Disaggregation of Revenue [Line Items]
Net Sales	168		54	1,297	1,449
Seed [Member] | Other oilseeds [Member]
Disaggregation of Revenue [Line Items]
Net Sales	44		57	469	514
Seed [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Net Sales	97		96	432	464
Crop Protection [Member]
Disaggregation of Revenue [Line Items]
Net Sales	1,230		1,396	4,516	4,756
Crop Protection [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Net Sales	70		122	183	227
Crop Protection [Member] | Herbicides [Member]
Disaggregation of Revenue [Line Items]
Net Sales	584		648	2,399	2,579
Crop Protection [Member] | Insecticides [Member]
Disaggregation of Revenue [Line Items]
Net Sales	322		334	1,158	1,111
Crop Protection [Member] | Fungicides [Member]
Disaggregation of Revenue [Line Items]
Net Sales	$ 254		$ 292	$ 776	$ 839