| transaction | 
            NEU | 
            Common Stock | 
            Award | 
            $0 | 
            +610 | 
            +2.74% | 
            $0.00 | 
            22.9K | 
            Feb 27, 2025 | 
            Direct | 
            F1, F2 | 
          
          
            | transaction | 
            NEU | 
            Common Stock | 
            Tax liability | 
            -$130K | 
            -230 | 
            -1% | 
            $563.12 | 
            22.7K | 
            Feb 27, 2025 | 
            Direct | 
            F3 | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            39.2K | 
            Feb 27, 2025 | 
            NewMarket Savings Plan | 
            F4 | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            5.09K | 
            Feb 27, 2025 | 
            Shares held by wife | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            46.4K | 
            Feb 27, 2025 | 
            Shares held as co-trustee fbo (among others reporting Floyd D. Gottwald) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            6.89K | 
            Feb 27, 2025 | 
            Shares held as co-trustee fbo children dtd. 12/16/1991 | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            63.6K | 
            Feb 27, 2025 | 
            2022 GRAT | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            225K | 
            Feb 27, 2025 | 
            2025 GRAT | 
            F2 | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            2.32K | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 1) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            1.87K | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 2) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            1.65K | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 3) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            1.56K | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 4) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            1.25K | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 5) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            955 | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 6) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            918 | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 7) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            576 | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 8) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            372 | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 9) | 
             | 
          
          
            | holding | 
            NEU | 
            Common Stock | 
             | 
             | 
             | 
             | 
             | 
            402 | 
            Feb 27, 2025 | 
            Shares held as trustee for grandchild (trust 10) | 
             |