Net Income Per Share - Reconciliation of Shares Used in Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
	Sep. 17, 2018	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net (loss) income attributable to IFF stockholders		$ (42)	$ 124
Adjustment related to (increase) decrease in redemption value of redeemable noncontrolling interests in excess of earnings allocated		(1)	6
Net (loss) income available to IFF stockholders		$ (43)	$ 130
Weighted average common shares outstanding (basic) (in shares)		206	112
Weighted average shares assuming dilution (diluted) (in shares)		206	113
Net income per share - basic (in dollars per share)		$ (0.21)	$ 1.16
Net income per share - diluted (in dollars per share)		(0.21)	1.15
Tangible Equity Units, Price for Shares Diluted	$ 0.3839	$ 0.3665	0.3839
Dilutive Securities, Effect on Basic Earnings Per Share		$ 1
Tangible Equity Units, Price for Shares Diluted	$ 0.3839	$ 0.3665	$ 0.3839
SPC portion of TEUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Adjustment for assumed dilution (in shares)		0	1