| Cover | Feb. 17, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K/A |
| Document Period End Date | Feb. 17, 2021 |
| Entity Registrant Name | BLUCORA, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 000-25131 |
| Entity Tax Identification Number | 91-1718107 |
| Entity Address, Address Line One | 3200 Olympus Blvd |
| Entity Address, Address Line Two | Suite 100 |
| Entity Address, City or Town | Dallas |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75019 |
| City Area Code | 972 |
| Local Phone Number | 870-6400 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | BCOR |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001068875 |
