Pension Plans and Other Post Employment Benefit Plans Basis of Fair Value Measurement (Details) - USD ($) $ in Millions	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Pension Trust Receivables	$ 214	[1]	$ 763	[2]
Pension Trust Payables	(434)	[3]	(646)	[4]
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17,835		16,941		$ 18,951
Investments Measured at Net Asset Value	2,469		2,414
Fair Value of Plan Assets, Excluding Trust Receivables and payables and assets measured at NAV	15,586		14,410
Pension Plan | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8,703		7,038
Pension Plan | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,768		7,320
Pension Plan | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	115		52		330
Pension Plan | Cash and Cash Equivalents [Domain]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,616		1,343
Pension Plan | Cash and Cash Equivalents [Domain] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,616		1,343
Pension Plan | Cash and Cash Equivalents [Domain] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Cash and Cash Equivalents [Domain] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,569		3,693
Investments Measured at Net Asset Value	36		37
Pension Plan | US Treasury and Government [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,569		3,693
Pension Plan | US Treasury and Government [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,579		2,956
Investments Measured at Net Asset Value	7
Pension Plan | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,576		2,952
Pension Plan | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3		4		14
Pension Plan | Asset-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	616		663
Pension Plan | Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	616		663
Pension Plan | Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments Measured at Net Asset Value	391		431
Pension Plan | Private Market Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3		2
Investments Measured at Net Asset Value	1,381		1,371
Pension Plan | Private Market Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Private Market Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Private Market Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3		2		1
Pension Plan | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28		33
Investments Measured at Net Asset Value	590		516
Pension Plan | Real Estate [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Real Estate [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28		33		93
Pension Plan | Derivative, Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		2
Pension Plan | Derivative, Asset [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Derivative, Asset [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		2
Pension Plan | Derivative, Asset [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Derivative, Liability [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		(19)
Pension Plan | Derivative, Liability [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Derivative, Liability [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		(19)
Pension Plan | Derivative, Liability [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	76		19
Pension Plan | Other Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Pension Plan | Other Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3		19
Pension Plan | Other Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	73		0		206
Non-US [Member] | Pension Plan | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,194		2,053
Investments Measured at Net Asset Value	32		39
Non-US [Member] | Pension Plan | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,189		2,043
Non-US [Member] | Pension Plan | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2		6
Non-US [Member] | Pension Plan | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3		4		2
UNITED STATES | Pension Plan | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,905	[5]	3,665	[6]
Investments Measured at Net Asset Value	32		20
UNITED STATES | Pension Plan | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,898	[5]	3,652	[6]
UNITED STATES | Pension Plan | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	[5]	4	[6]
UNITED STATES | Pension Plan | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 5	[5]	9	[6]	$ 14
Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Amount of Employer and Related Party Securities Included in Plan Assets, Percent	1.00%
Common Stock [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Amount of Employer and Related Party Securities Included in Plan Assets	$ 165		$ 126
Amount of Employer and Related Party Securities Included in Plan Assets, Percent			1.00%

[1] Primarily receivables for investments securities sold.

[2] Primarily receivables for investments securities sold.

[3] Primarily payables for investment securities purchased.

[4] Primarily payables for investment securities purchased.

[5] The Corteva pension plans directly held $165 million (approximately 1 percent of total plan assets) of Corteva, Inc. common stock at December 31, 2020.

[6] The Corteva pension plans directly held $126 million (approximately 1 percent of total plan assets) of Corteva, Inc. at December 31, 2019.