Revenue Disaggregation of Revenue - Products (Details) - USD ($) $ in Millions	3 Months Ended								4 Months Ended	8 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, 2017	Aug. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Net Sales	$ 2,983	$ 1,911	$ 5,556	$ 3,396	$ 2,815	$ 1,947	$ 5,731	$ 3,794	$ 3,790	$ 6,894	$ 13,846	$ 14,287
Seed [Member]
Disaggregation of Revenue [Line Items]
Net Sales									1,520	5,865	7,590	7,842
Seed [Member] | Corn [Member]
Disaggregation of Revenue [Line Items]
Net Sales									1,205	3,941	5,111	5,180
Seed [Member] | Soybean [Member]
Disaggregation of Revenue [Line Items]
Net Sales									163	1,384	1,371	1,494
Seed [Member] | Other oilseeds [Member]
Disaggregation of Revenue [Line Items]
Net Sales									143	423	561	607
Seed [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Net Sales									9	117	547	561
Crop Protection [Member]
Disaggregation of Revenue [Line Items]
Net Sales									2,270	1,029	6,256	6,445
Crop Protection [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Net Sales									147	0	253	382
Crop Protection [Member] | Herbicides [Member]
Disaggregation of Revenue [Line Items]
Net Sales									1,150	377	3,270	3,415
Crop Protection [Member] | Insecticides [Member]
Disaggregation of Revenue [Line Items]
Net Sales									567	108	1,652	1,506
Crop Protection [Member] | Fungicides [Member]
Disaggregation of Revenue [Line Items]
Net Sales									$ 406	$ 544	$ 1,081	$ 1,142