Note 1 - Condensed Consolidated Financial Statements - Basis of Presentation and Business Overview Capital and Liquidity (Details) (USD $)	9 Months Ended					9 Months Ended		3 Months Ended	9 Months Ended	1 Months Ended			9 Months Ended			1 Months Ended	7 Months Ended	1 Months Ended		1 Months Ended		3 Months Ended		9 Months Ended				9 Months Ended	12 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended	18 Months Ended	20 Months Ended	21 Months Ended
	Sep. 30, 2013 segment	Sep. 30, 2012	Sep. 30, 2013 Five Point Three Seven Five Percent Senior Notes due 2015 [Member]	Sep. 30, 2013 Nine Percent Notes Due 2017 [Member]	Sep. 30, 2013 Two Point Two Five Percent Convertible Notes Due 2019 [Member]	Sep. 30, 2013 Debt Exchange 2013 [Member] Five Point Three Seven Five Percent Senior Notes due 2015 [Member]	Sep. 30, 2013 Debt Exchange 2013 [Member] Nine Percent Notes Due 2017 [Member]	Sep. 30, 2013 Radian Guaranty [Member]	Sep. 30, 2013 Radian Guaranty [Member]	Jul. 31, 2013 Radian Asset Assurance [Member]	Jan. 31, 2013 Radian Asset Assurance [Member] 2012 FGIC Commutation [Member]	Feb. 28, 2013 Radian Asset Assurance [Member] Strategic Capital and Liquidity Initiatives [Member]	Sep. 30, 2013 Radian Asset Assurance [Member] CDO Termination [Member] counterparty contract	Sep. 30, 2013 Parent Company	Sep. 30, 2013 Parent Company Corporate Expenses and Interest Payments Due Within Twelve Months [Member]	Mar. 31, 2013 Common Stock Stock Offering 2013 [Member]	Sep. 30, 2013 Common Stock Stock Offering 2013 [Member]	Jan. 31, 2013 Reinsurance [Member] Radian Asset Assurance [Member] 2012 FGIC Commutation [Member]	Sep. 30, 2013 Convertible Debt [Member] Two Point Two Five Percent Convertible Notes Due 2019 [Member]	Mar. 31, 2013 Convertible Debt [Member] Debt Offering 2013 [Member] Two Point Two Five Percent Convertible Notes Due 2019 [Member]	Sep. 30, 2013 Convertible Debt [Member] Debt Offering 2013 [Member] Two Point Two Five Percent Convertible Notes Due 2019 [Member]	Sep. 30, 2013 Mortgage Insurance Segment	Sep. 30, 2012 Mortgage Insurance Segment	Sep. 30, 2013 Mortgage Insurance Segment	Sep. 30, 2012 Mortgage Insurance Segment	Dec. 31, 2012 Mortgage Insurance Segment	Sep. 30, 2013 Mortgage Insurance Segment Less Than [Member]	Sep. 30, 2013 Mortgage Insurance Segment Primary Mortgage Product [Member]	Dec. 31, 2012 Mortgage Insurance Segment Primary Mortgage Product [Member]	Sep. 30, 2013 Mortgage Insurance Segment First Lien Position [Member] Primary Mortgage Product [Member] 2013 Freddie Mac Agreement [Member]	Sep. 30, 2013 Mortgage Insurance Segment First Lien Position [Member] Primary Mortgage Product [Member] 2013 Freddie Mac Agreement [Member]	Dec. 31, 2011 Mortgage Insurance Segment First Lien Position [Member] Primary Mortgage Product [Member] 2013 Freddie Mac Agreement [Member] loan	Jul. 12, 2013 Mortgage Insurance Segment First Lien Position [Member] Primary Mortgage Product [Member] 2013 Freddie Mac Agreement [Member]	Aug. 30, 2013 Mortgage Insurance Segment First Lien Position [Member] Primary Mortgage Product [Member] 2013 Freddie Mac Agreement [Member]	Sep. 30, 2013 Mortgage Insurance Segment First Lien Position [Member] Primary Mortgage Product [Member] 2013 Freddie Mac Agreement [Member]	Jul. 31, 2013 Mortgage Insurance Segment First Lien Position [Member] Primary Mortgage Product [Member] 2013 Freddie Mac Agreement [Member] loan	Sep. 30, 2013 Minimum [Member]	Aug. 29, 2015 Minimum [Member] Mortgage Insurance Segment First Lien Position [Member] Primary Mortgage Product [Member] 2013 Freddie Mac Agreement [Member] Scenario, Forecast [Member]	Sep. 30, 2013 Maximum [Member]
Risk to Capital Line Items [Line Items]
Equity Method Investment, Ownership Percentage																																					20.00%		50.00%
Business Overview [Abstract]
Number of Operating Segments	2
Mortgage Insurance [Abstract]
Private Mortage 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 First Lien Insurance Risk In Force																						95.70%		95.70%
Total Risk In Force																						$ 41,000,000,000		$ 41,000,000,000
Percentage Of Pool Insurance On Domestic First-Lien Mortgages To Total First Lien Insurance Risk In Force																						4.10%		4.10%
NonTraditional Risk In Force																						115,000,000		115,000,000
Percentage Of Non-Traditional RIF To Total RIF																											1.00%
Business Conditions [Abstract]
Percentage Decrease In New Defaults																												19.00%	22.00%
Concentration Risk, Percentage																						43.00%		43.00%		55.00%
Maximum Loan To Value Percentage For G.S.E. Acquired Loans																						80.00%		80.00%
Minimum Percentage Of The Loans In Excess Of An 80% L.T.V. Which Must Be Retained By The Mortgage Originator Or Seller																						10.00%		10.00%
Capital Preservation and Liquidity Management Initiatives [Abstract]
Contingency Reserve Release											6,700,000	61,100,000
Reduction In Net Par Outstanding													3,400,000,000					822,200,000
Number Of Our Credit Derivative Counterparties That Excercised Their Termination Rights													4
Number of Corporate CDOs Terminated													9
Payment of Dividend by Subsidiary to Parent										36,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.375%	9.00%	2.25%	5.375%	9.00%														2.25%
Long-term Debt, Gross							195,500,000												400,000,000	400,000,000
Proceeds from Issuance of Long-term Debt																				389,800,000
Stock Issued During Period, Shares, New Issues																39,100,000
Sale of Stock, Price Per Share																$ 8
Proceeds from Issuance of Common Stock	299,410,000	0															299,400,000
Mortgage Loans on Real Estate, Number of Loans																																25,760
Mortgage Loans on Real Estate, Number of Re-Performing Loans																																				4,586
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure																															840,000,000
Total Consideration for Defaulted Loans																																		625,000,000
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid																						519,336,000	272,398,000	1,155,638,000	754,038,000								370,000,000
Net Consideration for Defaulted Loans																																		255,000,000
Restricted Investments Held as Collateral for Master Transaction Agreement																																		205,000,000
Termination Trigger Based on Amount of Restricted Investments																																						0
Restricted Investments Held as Collateral for Master Transaction Agreement, Gross																																		215,000,000
Not Final Loss Mitigation Activity																																			137,300,000
Loss Mitigation Activity																														2,400,000				10,000,000
Unrestricted Cash and Liquid Investments														822,100,000
Extinguishment of Debt, Amount						195,500,000
Risk to Capital, Entity's Intended Maximum								0.20	0.20
Mortgage Loans on Real Estate, Number of Delinquent Loans																																				9,756
Proceeds from Contributions from Affiliates														119,500,000	75,500,000
Unrestricted Cash and Liquid Investments Net of Subsidiaries Prepaid Corporate Expenses														702,600,000
Cash Distributed From Parent to Consolidated Subsidiary								$ 115,000,000	$ 230,000,000