| Document and Entity Information | Nov. 30, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 30, 2020 |
| Entity Registrant Name | STEPAN CO |
| Entity Central Index Key | 0000094049 |
| Entity Emerging Growth Company | false |
| Entity File Number | 1-4462 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 36-1823834 |
| Entity Address, Address Line One | Edens and Winnetka Road |
| Entity Address, City or Town | Northfield |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60093 |
| City Area Code | (847) |
| Local Phone Number | 446-7500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $1 par value |
| Trading Symbol | SCL |
| Security Exchange Name | NYSE |
