Note 10 - Losses and LAE Rescissions And Denials (Details) - USD ($) $ in Thousands	Aug. 29, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Rescissions And Denials [Line Items]
Reserve for losses and loss adjustment expense (“LAE”) (Note 10)		$ 726,169	$ 760,269
Mortgage Insurance Segment
Rescissions And Denials [Line Items]
Decrease To Our Loss Reserves Due To Estimated Rescissions And Denials		28,000	39,000
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount		13,500	14,300
Reserve for losses and loss adjustment expense (“LAE”) (Note 10)		726,169	760,269	$ 891,348	$ 976,399
2013 Freddie Mac Agreement [Member]
Rescissions And Denials [Line Items]
Reserve for losses and loss adjustment expense (“LAE”) (Note 10)		57,700
2013 Freddie Mac Agreement [Member] | Radian Guaranty Inc [Member]
Rescissions And Denials [Line Items]
Marketable Securities, Restricted		$ 64,300	$ 63,900
2013 Freddie Mac Agreement [Member] | Radian Guaranty Inc [Member] | Scenario, Forecast [Member]
Rescissions And Denials [Line Items]
Not Final Loss Mitigation Activity (less than)	$ 62,000