Note 11 - Losses and Loss Adjustment Expenses Rescissions And Denials (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) percentagepoint	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liability for Claims and Claims Adjustment Expense	$ 507,588	$ 760,269
2013 Freddie Mac Agreement [Member] | Radian Guaranty Inc [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Marketable Securities, Restricted	5,600	63,900
Mortgage Insurance Segment
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Decrease To Our Loss Reserves Due To Estimated Rescissions And Denials	21,000	39,000
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount	$ 10,400	14,300
Percentage Point Change In Severity Used In Assumption Shift Analysis | percentagepoint	1
Percentage Point Change In Severity Used In Assumption Shift Analysis | percentagepoint	1
First Lien Primary Claim Severity	97.60%
Impact To Loss Reserves Based On One Percentage Change In Primary Claim Severity	$ 4,800
Impact To Loss Reserves Based On One Percentage Change in Default To Claim Rate	14,200
Liability for Claims and Claims Adjustment Expense	$ 507,588	$ 760,269	$ 976,399	$ 1,560,032
Mortgage Insurance Segment | Primary Mortgage Product [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Weighted Average Default To Claim Rate Assumption Net Of Denials And Rescissions	31.00%	42.00%