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Document and Entity Information
Apr. 22, 2020
Cover [Abstract]  
Document Type 8-K
Amendment Flag false
Document Period End Date Apr. 22, 2020
Entity Registrant Name NEWMARKET CORPORATION
Entity Central Index Key 0001282637
Entity Incorporation, State or Country Code VA
Entity File Number 1-32190
Entity Tax Identification Number 20-0812170
Entity Address, Address Line One 330 South Fourth Street
Entity Address, City or Town Richmond,
Entity Address, State or Province VA
Entity Address, Postal Zip Code 23219
City Area Code 804
Local Phone Number 788-5000
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock, without par value
Trading Symbol NEU
Security Exchange Name NYSE
Entity Emerging Growth Company false