Note 8 - Reinsurance Excess-of-Loss Program (Details) $ in Thousands		1 Months Ended	12 Months Ended
		Nov. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	[2]	Dec. 31, 2016 USD ($)
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	[1]			$ 434,034
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				$ 435,148
Debt Instrument, Description of Variable Rate Basis				P1M
Eagle Re
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	[1]			$ 434,034
Number of Events				2
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				$ 435,148
Derivative Asset				1,100
Mortgage Insurance Segment
Risk In Force				56,700,000
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid				$ 215,948	$ 390,380		$ 417,562
Mortgage Insurance Segment | Radian Guaranty
Reinsurance Retention Policy, Option to Terminate, Period				5 years
Reinsurance Retention Policy, Option to Terminate, Period				10 years
Mortgage Insurance Segment | Radian Guaranty | Eagle Re
Proceeds from Issuance of Debt				$ 434,000
Risk Margin Component of Reinsurance Premium Payable, Percent				0.50
Reinsurance Retention Policy, Excess Retention, Amount Reinsured		$ 434,000
Risk In Force		9,100,000
Mortgage Insurance Segment | Radian Guaranty | Separate Third-Party Reinsurer
Reinsurance Retention Policy, Excess Retention, Amount Reinsured		21,400
XOL First Layer | Mortgage Insurance Segment | Radian Guaranty
Reinsurance Retention Policy, Amount Retained		204,900
XOL Second Layer | Mortgage Insurance Segment | Radian Guaranty | Eagle Re
Reinsurance Retention Policy, Reinsured Risk, Percentage				90.00%
XOL Second Layer | Mortgage Insurance Segment | Radian Guaranty | Separate Third-Party Reinsurer
Reinsurance Retention Policy, Reinsured Risk, Percentage				10.00%
XOL Second Layer | Mortgage Insurance Segment | Radian Guaranty | Eagle Re and Separate Third-Party Reinsurer
Reinsurance Retention Policy, Excess Retention, Amount Reinsured		214,100
XOL Third Layer | Mortgage Insurance Segment | Radian Guaranty | Eagle Re
Reinsurance Retention Policy, Excess Retention, Amount Reinsured		$ 241,400
Reinsurance Retention Policy, Reinsured Risk, Percentage				100.00%
On-Balance Sheet
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount				$ 1,114
On-Balance Sheet | Eagle Re
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[3]			1,114
Off-Balance Sheet
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[4]			434,034
Off-Balance Sheet | Eagle Re
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[4]			$ 434,034
Scenario, Forecast | Radian Guaranty
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid	[2]		$ 660,400

[1] Eagle Re’s assets are required to be invested in U.S. government money market funds, cash or U.S. Treasury securities. Eagle Re’s liabilities consist of its mortgage insurance-linked notes of $434.0 million, as described above.

[2] Includes the payment of $54.8 million made in connection with the scheduled final settlement of the Freddie Mac Agreement in the third quarter of 2017.

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

[4] Represents the maximum amount that would be payable in the future by Radian Guaranty to its policyholders on claims, without the benefit of any corresponding reinsurance recoverables, in the event of the combination of two events: (i) all of the assets in the reinsurance trust (consisting of U.S. government money market funds, cash or U.S. Treasury securities) have become worthless and (ii) $660.4 million of claims have been paid on the reinsured RIF.