| Document and Entity Information | Apr. 09, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | RADIAN GROUP INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000890926 |
| Document Type | 8-K |
| Document Period End Date | Apr. 9, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-11356 |
| Entity Tax Identification Number | 23-2691170 |
| Entity Address, Address Line One | 1500 Market Street |
| Entity Address, City or Town | Philadelphia |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 19102 |
| City Area Code | (215) |
| Local Phone Number | 231-1000 |
| Written Communications | false |
| Soliciting Material | true |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.001 par value per share |
| Trading Symbol | RDN |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
