Revenue Disaggregation of Revenue - Principal Product Groups (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Net Sales	$ 5,556	$ 3,396	$ 5,731	$ 8,952	$ 9,525
Seed [Member]
Disaggregation of Revenue [Line Items]
Net Sales	3,699		3,864	5,666	6,165
Seed [Member] | Corn [Member]
Disaggregation of Revenue [Line Items]
Net Sales	2,309		2,248	3,777	3,945
Seed [Member] | Soybean [Member]
Disaggregation of Revenue [Line Items]
Net Sales	998		1,214	1,129	1,395
Seed [Member] | Other oilseeds [Member]
Disaggregation of Revenue [Line Items]
Net Sales	200		194	425	457
Seed [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Net Sales	192		208	335	368
Crop Protection [Member]
Disaggregation of Revenue [Line Items]
Net Sales	1,857		1,867	3,286	3,360
Crop Protection [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Net Sales	52		82	113	105
Crop Protection [Member] | Herbicides [Member]
Disaggregation of Revenue [Line Items]
Net Sales	1,044		1,068	1,815	1,931
Crop Protection [Member] | Insecticides [Member]
Disaggregation of Revenue [Line Items]
Net Sales	459		448	836	777
Crop Protection [Member] | Fungicides [Member]
Disaggregation of Revenue [Line Items]
Net Sales	$ 302		$ 269	$ 522	$ 547