Note 7 - Reinsurance Excess-of-Loss Program (Details) $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended
		Apr. 30, 2019 USD ($)	Nov. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) arrangements	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) arrangements		Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Ceded Premiums Earned	[1]			$ 26,922	$ 16,068	$ 83,189	[2]	$ 48,945
Mortgage Insurance Segment
Risk In Force				60,400,000		$ 60,400,000
Radian Guaranty | Mortgage Insurance Segment
Reinsurance Retention Policy, Term of Coverage, Period						10 years
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	[3]			970,622		$ 970,622			$ 434,034
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				974,317		974,317			435,148
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment | On-Balance Sheet
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				3,695		3,695			1,114
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment | Off-Balance Sheet
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[4]			970,622		970,622			434,034
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment | Eagle Re 2018-1 (Primary)
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	[3]			408,586		408,586			434,034
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				410,079		410,079			435,148
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment | Eagle Re 2018-1 (Primary) | On-Balance Sheet
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[5]			1,493		1,493			1,114
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment | Eagle Re 2018-1 (Primary) | Off-Balance Sheet
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[4]			408,586		408,586			$ 434,034
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment | Eagle Re 2019-1 (Primary)
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	[3]			562,036		562,036
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				564,238		564,238
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment | Eagle Re 2019-1 (Primary) | On-Balance Sheet
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[5]			2,202		2,202
Excess-of-Loss Program | Radian Guaranty | Mortgage Insurance Segment | Eagle Re 2019-1 (Primary) | Off-Balance Sheet
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[4]			$ 562,036		$ 562,036
Excess-of-Loss Program | Radian Guaranty | Reinsurer Concentration Risk
Number of Fully Collateralized Reinsurance Arrangements with the Eagle Re Issuers | arrangements				2		2
Ceded Premiums Earned				$ 7,500		$ 18,400
Excess-of-Loss Program | Radian Guaranty | Reinsurer Concentration Risk | Mortgage Insurance Segment | Eagle Re 2018-1 (Primary)
Reinsurance Retention Policy, Excess Retention, Amount Reinsured			$ 434,000
Risk In Force			9,100,000
Excess-of-Loss Program | Radian Guaranty | Reinsurer Concentration Risk | Mortgage Insurance Segment | Eagle Re 2018-1 (Primary) | XOL First Layer
Reinsurance Retention Policy, Amount Retained			204,900
Excess-of-Loss Program | Radian Guaranty | Reinsurer Concentration Risk | Mortgage Insurance Segment | Separate Third-Party Reinsurer
Reinsurance Retention Policy, Excess Retention, Amount Reinsured			$ 21,400
Excess-of-Loss Program | Radian Guaranty | Reinsurer Concentration Risk | Mortgage Insurance Segment | Eagle Re 2019-1 (Primary)
Reinsurance Retention Policy, Excess Retention, Amount Reinsured		$ 562,000
Risk In Force		10,700,000
Proceeds from Issuance of Debt		562,000
Excess-of-Loss Program | Radian Guaranty | Reinsurer Concentration Risk | Mortgage Insurance Segment | Eagle Re 2019-1 (Primary) | XOL First Layer
Reinsurance Retention Policy, Amount Retained		$ 267,600

[1] Net of profit commission.

[2] Includes a cumulative adjustment to unearned premiums recorded in the second quarter of 2019 related to an update to the amortization rates used to recognize revenue for Single Premium Policies. See Note 3 for further information.

[3] 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 the Eagle Re Issuers consist of their mortgage insurance-linked notes, described above.

[4] Represents Radian Guaranty’s maximum exposure to loss in the event the VIE is unable to meet its obligations to us and our insurance subsidiaries would be liable to make claims payments to our policyholders. In the event that all of the assets in the reinsurance trust (consisting of U.S. government money market funds, cash or U.S. Treasury securities) were to lose their value and the VIE is unable to make its payments to us, our maximum potential loss would be the amount of mortgage insurance claim payments for losses on the insured policies, net of the aggregate reinsurance payments already received, up to the full aggregate excess-of-loss reinsurance coverage amount. In the same scenario, the related embedded derivative would no longer have value.

[5] Represents the fair value of the related embedded derivative, included in other assets in our condensed consolidated balance sheets.