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Restructuring and Other Charges - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 16	$ 1	$ 54	$ 6
IFF Productivity Program
Restructuring Cost and Reserve [Line Items]
Additional Charges (Reversals), Net			54
IFF Productivity Program \| Minimum \| Taste, Food Ingredients, Health And Biosciences, And Scent
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	100		100		$ 100
IFF Productivity Program \| Maximum \| Taste, Food Ingredients, Health And Biosciences, And Scent
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	120		120		120
Employee Severance \| IFF Productivity Program
Restructuring Cost and Reserve [Line Items]
Additional Charges (Reversals), Net	$ 16		$ 54
Restructuring Costs					57
Fixed Asset Write Down [Member] \| IFF Productivity Program
Restructuring Cost and Reserve [Line Items]
Restructuring Costs					$ 20