Fair Value Measurements Nonrecurring Fair Value (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-Lived Intangible Assets, Gross		$ 4,117	$ 4,474	$ 4,117	$ 4,152
Equity Method Investment, Other than Temporary Impairment		41		41
Technology-Based Intangible Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-Lived Intangible Assets, Gross			0
Other Intangible Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-Lived Intangible Assets, Gross			0
In Process Research and Development [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges			(47)	(85)
Indefinite-lived Intangible Assets (Excluding Goodwill), Fair Value Disclosure		450	0	450
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure		51		51
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investment, Other than Temporary Impairment				(41)
Technology-Based Intangible Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges			(1)
Other Intangible Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-Lived Intangible Assets, Gross	[1],[2]	$ 530	401	$ 530	$ 538
Asset Impairment Charges			$ (6)

[1] Primarily consists of sales and farmer networks, marketing and manufacturing alliances and noncompetition agreements.

[2] Refer to discussion of interim impairment analysis completed below.