Goodwill and Other Intangible Assets Goodwill by Segment (Details) - USD ($) $ in Millions		3 Months Ended		4 Months Ended	5 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	May 31, 2019		Sep. 30, 2019		Sep. 30, 2018	Dec. 31, 2018
Goodwill [Line Items]
Goodwill Beginning Balance				$ 10,179	$ 10,193		$ 10,193
Currency Translation Adjustment				(11)	(28)
Other goodwill adjustments and acquisitions					14
Segment realignment					0
Goodwill Ending Balance		$ 10,168	$ 10,203	10,168			10,168		$ 10,203
Goodwill impairment charge		0	4,503				0		4,503
Agriculture [Member]
Goodwill [Line Items]
Goodwill Beginning Balance				0	10,193	[1]	10,193	[1]
Currency Translation Adjustment				0	(28)
Other goodwill adjustments and acquisitions	[2]				14
Segment realignment					(10,179)
Goodwill Ending Balance		0		0			0
Goodwill, Impaired, Accumulated Impairment Loss										$ 4,503
Goodwill impairment charge			4,503						4,503
Crop Protection [Member]
Goodwill [Line Items]
Goodwill Beginning Balance				4,726	0		0
Currency Translation Adjustment				(5)	0
Other goodwill adjustments and acquisitions					0
Segment realignment					4,726
Goodwill Ending Balance		4,721		4,721			4,721
Seed [Member]
Goodwill [Line Items]
Goodwill Beginning Balance				5,453	0		0
Currency Translation Adjustment				(6)	0
Other goodwill adjustments and acquisitions					0
Segment realignment					$ 5,453
Goodwill Ending Balance		5,447		$ 5,447			5,447
In Process Research and Development [Member]
Goodwill [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		54	85				54		85
Impairment of Intangible Assets Indefinite lived Excluding Goodwill After Tax		$ 41	$ 66				$ 41		$ 66

[1] Net of accumulated impairment losses of $4,503 million.

[2] Primarily consists of the acquisition of a distributor in Greece.