Note 8 - Reinsurance Excess-of-Loss Program (Details) - Mortgage Insurance Segment $ in Thousands		1 Months Ended			12 Months Ended
		Feb. 29, 2020 USD ($)	Apr. 30, 2019 USD ($)	Nov. 30, 2018 USD ($)	Dec. 31, 2019 USD ($) arrangements	Dec. 31, 2018 USD ($)
Risk In Force					$ 60,900,000
Radian Guaranty
Reinsurance Retention Policy, Term of Coverage, Period					10 years
Number of Fully Collateralized Reinsurance Arrangements with the Eagle Re Issuers | arrangements					2,000
Excess-of-Loss Program | Radian Guaranty
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	[1]				$ 865,454	$ 434,034
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	[1]				865,454	434,034
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2019-1 (Primary)
Risk In Force			$ 10,705,000		8,409,000
Reinsurance Retention Policy, Excess Retention, Amount Reinsured			562,000		487,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	[1]				508,449	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	[1]				508,449	0
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2018-1 (Primary)
Risk In Force				$ 9,109,000	7,026,000
Reinsurance Retention Policy, Excess Retention, Amount Reinsured	[2]			434,000	343,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	[1]				357,005	434,034
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	[1]				357,005	434,034
Excess-of-Loss Program | Radian Guaranty | Separate Third-Party Reinsurer
Reinsurance Retention Policy, Excess Retention, Amount Reinsured				21,400
Excess-of-Loss Program | Radian Guaranty | Eagle Re (Primary)
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount					400	$ 1,100
Excess-of-Loss Program | XOL First Layer | Radian Guaranty | Eagle Re 2019-1 (Primary)
Reinsurance Retention Policy, Amount Retained			$ 268,000		267,000
Excess-of-Loss Program | XOL First Layer | Radian Guaranty | Eagle Re 2018-1 (Primary)
Reinsurance Retention Policy, Amount Retained				$ 205,000	$ 204,000
Reinsurer Concentration Risk | Subsequent Event | Excess-of-Loss Program | Radian Guaranty | Eagle Re 2020-1 (Primary)
Risk In Force		$ 9,900,000
Reinsurance Retention Policy, Excess Retention, Amount Reinsured		488,400
Proceeds from Issuance of Debt		$ 488,400

[1] Assets held by the Eagle Re Issuers are required to be invested in U.S. government money market funds, cash or U.S. Treasury securities. Liabilities of Eagle Re Issuers consist of their mortgage insurance-linked notes, as described above.

[2] Excludes a separate excess-of-loss reinsurance agreement entered into by Radian Guaranty that initially provided up to $21.4 million of coverage.