Note 10 - Losses and LAE Rescissions And Denials (Details) - USD ($) $ in Thousands		1 Months Ended
	Aug. 29, 2017	Oct. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Rescissions And Denials [Line Items]
Reserve for losses and loss adjustment expense (“LAE”) (Note 10)			$ 821,934	$ 976,399
Mortgage Insurance Segment
Rescissions And Denials [Line Items]
Decrease To Our Loss Reserves Due To Estimated Rescissions And Denials			59,000	69,000
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount			16,800	26,600
Reserve for losses and loss adjustment expense (“LAE”) (Note 10)			821,934	976,399	$ 1,098,570	$ 1,560,032
2013 Freddie Mac Agreement [Member]
Rescissions And Denials [Line Items]
Reserve for losses and loss adjustment expense (“LAE”) (Note 10)			57,000
2013 Freddie Mac Agreement [Member] | Radian Guaranty Inc [Member]
Rescissions And Denials [Line Items]
Marketable Securities, Restricted			$ 75,800	$ 74,700
2013 Freddie Mac Agreement [Member] | Radian Guaranty Inc [Member] | Scenario, Forecast [Member]
Rescissions And Denials [Line Items]
Not Final Loss Mitigation Activity (less than)	$ 64,000
Subsequent Event [Member] | 2013 Freddie Mac Agreement [Member]
Rescissions And Denials [Line Items]
Increase (Decrease) in Restricted Cash and Investments for Operating Activities		$ 11,700