Reinsurance - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Radian Guaranty
Ceded Credit Risk [Line Items]
Funds held under reinsurance agreements, asset	$ 304	$ 274
Mortgage Insurance revenues
Ceded Credit Risk [Line Items]
Direct primary mortgage insurance risk in force	$ 71,800	$ 69,700
Excess-of-Loss Program | Radian Guaranty
Ceded Credit Risk [Line Items]
Percent of reinsurance coverage threshold (in percent)	0.10
Maximum | Mortgage Insurance revenues | Radian Guaranty
Ceded Credit Risk [Line Items]
Reinsurance retention policy, term of coverage, period	12 years 6 months
Maximum | 2024 QSR Agreement
Ceded Credit Risk [Line Items]
Direct primary mortgage insurance risk in force	$ 4,300
Maximum | Excess-of-Loss Program | Radian Guaranty
Ceded Credit Risk [Line Items]
Right to termination on or after option call date, period after issuance of insurance-linked notes	7 years
Minimum | Mortgage Insurance revenues | Radian Guaranty
Ceded Credit Risk [Line Items]
Reinsurance retention policy, term of coverage, period	10 years
Minimum | Excess-of-Loss Program | Radian Guaranty
Ceded Credit Risk [Line Items]
Right to termination on or after option call date, period after issuance of insurance-linked notes	5 years