Note 1 - Description of Business and Recent Developments Capital and Liquidity (Details) (USD $)	12 Months Ended			1 Months Ended				8 Months Ended	10 Months Ended	0 Months Ended
	Dec. 31, 2014 segment	Dec. 31, 2013	Dec. 31, 2012	Feb. 28, 2014	Feb. 28, 2015	May 31, 2014	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 22, 2014
Business Overview [Abstract]
Number of Reportable Segments	2
Business Combination, Description [Abstract]
Goodwill	$ 191,932,000							$ 191,932,000
Business Combination, Acquisition Related Costs	6,680,000	0	0
Insurance Regulatory Capital Requirements [Abstract]
Risk To Capital Ratio, Regulatory Maximum	25							25
Number of Days Until Eligibility Requirements Become Effective After Final Publication	180 days
Transition Period for Compliance to New Eligibility Requirements	2 years
Capital Stock [Abstract]
Issuance of common stock	247,188,000	299,410,000	0
Parent Company
Capital Stock [Abstract]
Issuance of common stock	247,188,000	299,410,000	0
Radian Guaranty [Member]
Insurance Regulatory Capital Requirements [Abstract]
Percentage of New Insurance Written Attributable To States With Statutory Or Regulatory Risk Based Capital Requirements	56.30%	55.70%
Proceeds from Contributions from Parent		230,000,000	100,000,000	100,000,000
Risk-to-capital	17.9	19.5						17.9	19.5
Subsequent Event [Member] | Radian Guaranty [Member]
Insurance Regulatory Capital Requirements [Abstract]
Proceeds from Contributions from Parent					100,000,000
Common Stock
Capital Stock [Abstract]
Stock Issued During Period, Shares, New Issues						17,825,000	39,100,000
Shares Issued, Price Per Share						$ 14.50
Issuance of common stock								247,200,000	299,400,000
State Insurance Regulations [Member]
Insurance Regulatory Capital Requirements [Abstract]
Number Of States That Have A Statutory Or Regulatory Risk Based Capital Requirement	16							16
Non RBC States [Member] | Maximum [Member]
Insurance Regulatory Capital Requirements [Abstract]
Capital Required for Capital Adequacy	5,000,000							5,000,000
Non RBC States [Member] | Minimum [Member]
Insurance Regulatory Capital Requirements [Abstract]
Capital Required for Capital Adequacy	1,000,000							1,000,000
Bank of America Settlement Agreement [Member] | Radian Guaranty [Member]
BAC Settlement Agreement [Abstract]
Loss Contingency, Settlement Agreement, Percentage of Subject Loans Not Held by Insureds or Are Non-GSE Investors	12.00%							12.00%
Clayton Holdings, LLC [Member]
Business Combination, Description [Abstract]
Payments to Acquire Businesses, Gross										312,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets										152,400,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities										31,803,000
Goodwill										191,932,000
Business Acquisition, Goodwill, Expected Number of Years For Tax Deduction	15 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents										16,521,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Restricted Cash										1,591,000
Business Combination, Acquired Receivables, Fair Value										11,236,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment										2,419,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill										102,750,000
Business Combination, Other Assets, Fair Value										17,852,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net										312,498,000
Business Combination, Acquisition Related Costs	6,500,000
Clayton Holdings, LLC [Member] | Pro Forma [Member]
Business Combination, Description [Abstract]
Business Acquisition, Goodwill, Expected Tax Deductible Amount	189,000,000							189,000,000
Sale of Radian Asset Assurance [Member]
Business Overview [Abstract]
Sale of Stock, Percentage of Ownership before Transaction											100.00%
Sale of Radian Asset Assurance [Member] | Parent Company
Business Overview [Abstract]
Sale of Stock, Percentage of Ownership before Transaction											100.00%
Financial Guaranty and Discontinued Operations [Abstract]
Disposal Group, Including Discontinued Operation, Consideration											810,000,000
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds											790,000,000
Mortgage Insurance Segment
Mortgage Insurance [Abstract]
Private Mortgage Insurance Protects Lenders For Loans Made With This Maximum Downpayment Percentage	20.00%							20.00%
Percentage Of Primary Insurance On Domestic First-Lien Mortgages To Total Risk In Force	96.60%							96.60%
Risk In Force	44,800,000,000							44,800,000,000
Percentage Of Pool Insurance On Domestic First-Lien Mortgages To Total Risk In Force	3.20%							3.20%
Nontraditional Risk In Force	73,000,000							73,000,000
Business Combination, Description [Abstract]
Goodwill	$ 0							$ 0
Mortgage Insurance Segment | Maximum [Member]
Mortgage Insurance [Abstract]
Percentage Of Non-Traditional RIF To Total RIF	1.00%							1.00%
Mortgage Insurance Segment | Bank of America Settlement Agreement [Member]
BAC Settlement Agreement [Abstract]
Loss Contingency, Settlement Agreement, Percentage of Subject Loans Not Held by Insureds or Are Non-GSE Investors	12.00%							12.00%