Reinsurance - Narrative (Details) $ in Millions		6 Months Ended
	Jul. 01, 2023 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Radian Guaranty
Ceded Credit Risk [Line Items]
Funds held under reinsurance agreements, asset		$ 283	$ 274
Mortgage Insurance revenues
Ceded Credit Risk [Line Items]
Direct primary mortgage insurance risk in force		$ 71,100	$ 69,700
2023 QSR Agreement | Radian Guaranty
Ceded Credit Risk [Line Items]
Ceding commission %	20.00%
2024 QSR Agreement
Ceded Credit Risk [Line Items]
Percentage of policies ceded to reinsurer (in percent)		0.25
Risk In Force		$ 4,300
2024 QSR Agreement | Radian Guaranty
Ceded Credit Risk [Line Items]
Ceding commission %		20.00%
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 | 2023 QSR Agreement
Ceded Credit Risk [Line Items]
Direct primary mortgage insurance risk in force	$ 3,000
Maximum | 2023 QSR Agreement | Radian Guaranty
Ceded Credit Risk [Line Items]
Profit commission %	55.00%
Maximum | 2024 QSR Agreement | Radian Guaranty
Ceded Credit Risk [Line Items]
Profit commission %		59.00%
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