| NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            225K | 
            $178M | 
            $791.23 | 
            Aug 25, 2025 | 
            2025 GRAT | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            63.6K | 
            $50.3M | 
            $791.23 | 
            Aug 25, 2025 | 
            2022 GRAT | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            46.4K | 
            $36.7M | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as co-trustee fbo (among others reporting Floyd D. Gottwald) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            39.6K | 
            $31.3M | 
            $791.23 | 
            Aug 25, 2025 | 
            NewMarket Savings Plan | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            20.6K | 
            $16.3M | 
            $791.23 | 
            Aug 25, 2025 | 
            Direct | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            6.89K | 
            $5.45M | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as co-trustee fbo children dtd. 12/16/1991 | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            5.09K | 
            $4.02M | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held by reporting person's wife | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            2.32K | 
            $1.83M | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 1) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            1.87K | 
            $1.48M | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 2) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            1.68K | 
            $1.33M | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 3) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            1.56K | 
            $1.23M | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 4) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            1.29K | 
            $1.02M | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 5) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            984 | 
            $779K | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 7) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            955 | 
            $756K | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 6) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            576 | 
            $456K | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 8) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            438 | 
            $347K | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 9) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            402 | 
            $318K | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 10) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            198 | 
            $157K | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 12) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            132 | 
            $104K | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 11) | 
          
          
            | NEWMARKET CORP | 
            Chairman, President & CEO, Director | 
            Common Stock | 
            132 | 
            $104K | 
            $791.23 | 
            Aug 25, 2025 | 
            Shares held as trustee for grandchild (trust 13) |