v3.25.3

Cover	Oct. 30, 2025
Document Type	8-K
Amendment Flag	false
Document Period End Date	Oct. 30, 2025
Entity File Number	1-10551
Entity Registrant Name	OMNICOM GROUP INC.
Entity Central Index Key	0000029989
Entity Tax Identification Number	13-1514814
Entity Incorporation, State or Country Code	NY
Entity Address, Address Line One	280 Park Avenue
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10017
City Area Code	212
Local Phone Number	415-3600
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Entity Emerging Growth Company	false
Common Stock, par value $0.15 per share
Title of 12(b) Security	Common Stock, par value $0.15 per share
Trading Symbol	OMC
Security Exchange Name	NYSE
0.800% Senior Notes due 2027
Title of 12(b) Security	0.800% Senior Notes due 2027
Trading Symbol	OMC/27
Security Exchange Name	NYSE
1.400% Senior Notes due 2031
Title of 12(b) Security	1.400% Senior Notes due 2031
Trading Symbol	OMC/31
Security Exchange Name	NYSE
3.700% Senior Notes due 2032
Title of 12(b) Security	3.700% Senior Notes due 2032
Trading Symbol	OMC/32
Security Exchange Name	NYSE
2.250% Senior Notes due 2033
Title of 12(b) Security	2.250% Senior Notes due 2033
Trading Symbol	OMC/33
Security Exchange Name	NYSE

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For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

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The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

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Address Line 1 such as Attn, Building Name, Street Name

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Name of the state or province.

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A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

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The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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OMNICOM GROUP INC. 8-K