| Cover | Mar. 30, 2021 |
| Cover [Abstract] | |
| Entity Central Index Key | 0001026655 |
| Amendment Flag | false |
| Document Type | 8-K |
| Document Period End Date | Mar. 30, 2021 |
| Entity Registrant Name | Core Molding Technologies, Inc. |
| Entity File Number | 001-12505 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 31-1481870 |
| Entity Address, Address Line One | 800 Manor Park Drive |
| Entity Address, City or Town | Columbus |
| Entity Address, State or Province | OH |
| Entity Address, Postal Zip Code | 43228-0183 |
| City Area Code | 614 |
| Local Phone Number | 870-5000 |
| Entity Emerging Growth Company | false |
| Entity Listings [Line Items] | |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Current Fiscal Year End Date | --12-31 |
| Common Stock [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Common Stock, par value $0.01 |
| Trading Symbol | CMT |
| Security Exchange Name | NYSEAMER |
| Preferred Stock [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Preferred Stock purchase rights, par value $0.01 |
| Trading Symbol | N/A |
| Security Exchange Name | NYSEAMER |
