Note 4 - Fair Value of Financial Instruments Impact of Non-Performance Risk on Fair Value Disclosure (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 basispoint		Dec. 31, 2013 basispoint		Mar. 31, 2013 basispoint	Dec. 31, 2012 basispoint
Five Year CDS Spread Details [Abstract]
Derivative Liability, Fair Value, Gross Liability	$ 388.8		$ 445.1
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	181.3		209.9
Derivative liabilities, net	207.5		235.2
Fair Value, Concentration of Risk, Market Risk Management, Additional Details [Member]
Five Year CDS Spread Details [Abstract]
Radian Group's five year CDS Spread (in basis points)	288		323		513	913
Number of Years for CDS Spread Related to Non Performance Risk In Fair Value Disclosure	5 years
Market View Of The Probability That Registrant Will Default In The Next Five Years	21.10%		22.90%
Number Of Years In Which The Market Believes Radian Group Will Default	5 years
Change in Impact of Non Performance Risk on Fair Value of Financial Instruments	28.6
Corporate Collateralized Debt Obligations [Member]
Five Year CDS Spread Details [Abstract]
Derivative Liability, Fair Value, Gross Liability	26.0		30.4
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	23.5		29.0
Derivative liabilities, net	2.5		1.4
Non Corporate Collateralized Debt Obligations And Other Derivative Transactions [Member]
Five Year CDS Spread Details [Abstract]
Derivative Liability, Fair Value, Gross Liability	357.6	[1]	409.7	[1]
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	155.7	[1]	178.7	[1]
Derivative liabilities, net	201.9	[1]	231.0	[1]
NIMS Related [Member]
Five Year CDS Spread Details [Abstract]
Derivative Liability, Fair Value, Gross Liability	5.2	[2]	5.0	[2]
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	2.1	[2]	2.2	[2]
Derivative liabilities, net	$ 3.1	[2]	$ 2.8	[2]

[1] Includes the net fair value liability recorded within derivative assets and derivative liabilities and the net fair value liabilities included in our consolidated VIEs.

[2] Includes NIMS VIE debt.