Employee Benefits - Weighted Average Assumptions Used to Determine Postretirement Benefit Expense and Obligation (Detail)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Expense [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.80%	4.00%
Current medical cost trend rate	6.50%	6.75%
Ultimate medical cost trend rate	4.75%	4.75%
Medical cost trend rate decreases to ultimate rate in year	2021	2021
Liability [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.90%	4.80%
Current medical cost trend rate	5.80%	6.50%
Ultimate medical cost trend rate	4.75%	4.75%
Medical cost trend rate decreases to ultimate rate in year	2023	2021

The current medical cost trend rate utilized to determine postretirement benefit expense.

No definition available.

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Namespace Prefix:	iff_
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Period Type:	duration

- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(1)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

+ Details

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- Details

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- Definition

The ultimate trend rate for health care costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (l)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

+ Details

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- Definition

Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (l)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

+ Details

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