Note 13 - Statutory Information Statutory Information (Details) (USD $)		3 Months Ended		12 Months Ended		3 Months Ended				1 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2013 Radian Guaranty [Member]		Dec. 31, 2012 Radian Guaranty [Member]		Sep. 30, 2012 Radian Asset Assurance [Member]	Mar. 31, 2013 Radian Asset Assurance [Member]	Mar. 31, 2013 Radian Asset Assurance [Member] Terminated TruPs Bonds Subject To An Event Of Default Occurring And Continuing After 2016 or 2017 [Member] derivative	Mar. 31, 2013 Radian Asset Assurance [Member] Terminated TruPs Bonds [Member]	Jul. 31, 2013 Radian Asset Assurance [Member] Scenario, Forecast [Member]	Mar. 31, 2013 Parent Company	Mar. 31, 2013 Mortgage Insurance Segment Radian Guaranty [Member]	Mar. 31, 2013 State Insurance Regulations [Member] Mortgage Insurance Segment state
Statutory Accounting Practices [Line Items]
Number Of States That Have A Statutory Or Regulatory Risk Based Capital Requirement													16
Risk To Capital Ratio, Regulatory Maximum													0.25
Percentage of New Insurance Written Attributable To States With Statutory Or Regulatory Risk Based Capital Requirements												55.00%
Unrestricted Cash and Liquid Investments	$ 886,400,000										$ 886,400,000
Statutory net (loss) income		(1,800,000)		(175,900,000)
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		1,098,300,000		926,000,000			1,200,000,000
Contingency Reserve		7,400,000		0
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		1,105,700,000		926,000,000
Net Risk In Force		20,537,100,000	[1]	19,226,700,000	[1]
Risk To Capital Ratio		0.186		0.208
Risk to Capital, Entity's Intended Maximum		0.20
Capital Contributions		115,000,000
Claims Paying Resources							1,700,000,000
Payment of Dividend by Subsidiary to Parent						54,000,000				37,000,000
Statutory Salvage Recovery									76,800,000
Number Of Trups CDOs Terminated								4
Restricted Cash and Cash Equivalents	$ 1,200,000,000

[1] RIF, net excludes risk ceded through reinsurance contracts and RIF on defaulted loans.