Nature of Operations and Summary of Accounting Policies - Revision of Previously Issued Financial Statements, Impacts to Consolidated Statements of Income (Loss) and Comprehensive Income (Loss) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended					6 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales	$ 2,764	$ 2,771	$ 2,925			$ 5,607	$ 5,788		$ 8,713	$ 10,890	$ 11,484	$ 11,479
Gross profit	1,030	980	1,052			2,065	2,092		3,144	3,938	4,124	3,681
Loss on assets classified as held for sale										115	317	0
Earnings from continuing operations, before income tax expense										(412)	308	(2,518)
Income Tax Expense										(53)	41	69
Net (loss) income										(359)	267	(2,587)
Net (loss) income available to IFF shareholders										$ (361)	$ 263	$ (2,591)
Net income per share - basic (in dollars per share)										$ (1.41)	$ 1.04	$ (10.14)
Net income per share - diluted (in dollars per share)										$ (1.41)	$ 1.04	$ (10.14)
Comprehensive income (loss)										$ 738	$ (364)	$ (2,285)
Comprehensive income (loss) attributable to IFF shareholders										$ 736	(368)	(2,289)
Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales				$ (2,889)	$ (2,899)			$ 8,301			11,484	11,479
Gross profit				(1,068)	(1,024)			3,048			4,124	3,681
Loss on assets classified as held for sale		33	32	282	0		282		314		347	0
Earnings from continuing operations, before income tax expense	534	(115)	95	183	115	(460)	298	(434)	393		278	(2,518)
Income Tax Expense	(78)	(69)	35	11	54	(55)	65	(44)	100		31	45
Net (loss) income	612	(46)	60	172	61	(405)	233	(390)	293		247	(2,563)
Net (loss) income available to IFF shareholders	$ 612	$ (46)	$ 59	$ 170	$ 60	$ (406)	$ 230	$ (392)	$ 289		$ 243	$ (2,567)
Net income per share - basic (in dollars per share)	$ 2.39	$ (0.18)	$ 0.23	$ 0.67	$ 0.23	$ (1.59)	$ 0.90	$ (1.53)	$ 1.13		$ 0.95	$ (10.05)
Net income per share - diluted (in dollars per share)	$ 2.38	$ (0.18)	$ 0.23	$ 0.66	$ 0.23	$ (1.59)	$ 0.90	$ (1.53)	$ 1.13		$ 0.95	$ (10.05)
Comprehensive income (loss)	$ 1,320	$ (813)	$ 615	$ 48	$ (234)	$ 707	$ (186)	$ 674	$ 429		$ (384)	$ (2,261)
Comprehensive income (loss) attributable to IFF shareholders	1,320	(813)	614	46	(235)	706	(189)	672	425		(388)	(2,265)
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales	0	0	0	0	0	0	0	0	0		0	0
Gross profit	0	0	0	0	0	0	0	0	0		0	0
Loss on assets classified as held for sale		0	0	(30)	0		(30)		(30)		(30)	0
Earnings from continuing operations, before income tax expense	(30)	0	0	30	0	(30)	30	0	30		30	0
Income Tax Expense	(17)	14	1	6	(11)	(17)	(5)	(13)	(4)		10	24
Net (loss) income	(13)	(14)	(1)	24	11	(13)	35	13	34		20	(24)
Net (loss) income available to IFF shareholders	$ (13)	$ (14)	$ (1)	$ 24	$ 11	$ (13)	$ 35	$ 13	$ 34		$ 20	$ (24)
Net income per share - basic (in dollars per share)	$ (0.05)	$ (0.05)	$ 0	$ 0.09	$ 0.05	$ (0.05)	$ 0.14	$ 0.05	$ 0.14		$ 0.09	$ (0.09)
Net income per share - diluted (in dollars per share)	$ (0.05)	$ (0.05)	$ 0	$ 0.10	$ 0.05	$ (0.05)	$ 0.14	$ 0.05	$ 0.14		$ 0.09	$ (0.09)
Comprehensive income (loss)	$ (13)	$ (14)	$ (1)	$ 24	$ 11	$ (13)	$ 35	$ 13	$ 34		$ 20	$ (24)
Comprehensive income (loss) attributable to IFF shareholders	(13)	(14)	(1)	24	11	(13)	35	13	34		20	(24)
Revision Of Prior Period, Revised Amount
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales				(2,889)	(2,899)			8,301			11,484	11,479
Gross profit				(1,068)	(1,024)			3,048			4,124	3,681
Loss on assets classified as held for sale		33	32	252	0		252		284		317	0
Earnings from continuing operations, before income tax expense	504	(115)	95	213	115	(490)	328	(434)	423		308	(2,518)
Income Tax Expense	(95)	(55)	36	17	43	(72)	60	(57)	96		41	69
Net (loss) income	599	(60)	59	196	72	(418)	268	(377)	327		267	(2,587)
Net (loss) income available to IFF shareholders	$ 599	$ (60)	$ 58	$ 194	$ 71	$ (419)	$ 265	$ (379)	$ 323		$ 263	$ (2,591)
Net income per share - basic (in dollars per share)	$ 2.34	$ (0.23)	$ 0.23	$ 0.76	$ 0.28	$ (1.64)	$ 1.04	$ (1.48)	$ 1.27		$ 1.04	$ (10.14)
Net income per share - diluted (in dollars per share)	$ 2.33	$ (0.23)	$ 0.23	$ 0.76	$ 0.28	$ (1.64)	$ 1.04	$ (1.48)	$ 1.27		$ 1.04	$ (10.14)
Comprehensive income (loss)	$ 1,307	$ (827)	$ 614	$ 72	$ (223)	$ 694	$ (151)	$ 687	$ 463		$ (364)	$ (2,285)
Comprehensive income (loss) attributable to IFF shareholders	$ 1,307	$ (827)	$ 613	$ 70	$ (224)	$ 693	$ (154)	$ 685	$ 459		$ (368)	$ (2,289)

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