Reinsurance - Narrative (Details) - Radian Guaranty $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) reinsuranceArrangement	Dec. 31, 2021 USD ($)
Ceded Credit Risk [Line Items]
Funds held under reinsurance agreements, asset | $	$ 134.3	$ 167.9
Maximum | Mortgage
Ceded Credit Risk [Line Items]
Reinsurance retention policy, term of coverage, period	12 years 6 months
Minimum
Ceded Credit Risk [Line Items]
Reinsurance retention policy, term of coverage, period	10 years
Excess-of-Loss Program
Ceded Credit Risk [Line Items]
Number of fully collateralized reinsurance arrangements with the eagle re issuers | reinsuranceArrangement	6