| Cover Page | Feb. 26, 2025 |
| Cover [Abstract] | |
| Entity Central Index Key | 0000071829 |
| Document Type | 8-K |
| Document Period End Date | Feb. 26, 2025 |
| Entity Registrant Name | NPK International Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-02960 |
| Entity Tax Identification Number | 72-1123385 |
| Entity Address, Address Line One | 9320 Lakeside Boulevard, |
| Entity Address, Address Line Two | Suite 100 |
| Entity Address, City or Town | The Woodlands, |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 77381 |
| City Area Code | 281 |
| Local Phone Number | 362-6800 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Title of 12(b) Security | Common Stock, $0.01 par value |
| Trading Symbol | NPKI |
| Security Exchange Name | NYSE |
