Note 4 - Derivative Instruments Derivative Contract (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
NIMS related and other [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	0	[1]
Notional Amount of Derivatives	$ 0	[1]
Derivative assets (liabilities), at fair value, net	1.8	[1]
Corporate collateralized debt obligations (CDO's)[Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	74
Notional Amount of Derivatives	29,493.5
Derivative assets (liabilities), at fair value, net	(5.1)
Non Corporate CDOS and other derivative transactions[Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	55
Notional Amount of Derivatives	5,985.3
Derivative assets (liabilities), at fair value, net	(76.5)
Trust Preferred Securities (TruPs) [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	19
Notional Amount of Derivatives	1,894.2
Derivative assets (liabilities), at fair value, net	(26.5)
CDOS of commercial mortgage backed securities (CMBS)[Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	4
Notional Amount of Derivatives	1,831.0
Derivative assets (liabilities), at fair value, net	(27.1)
Structured finance [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	8
Notional Amount of Derivatives	716.6
Derivative assets (liabilities), at fair value, net	(13.4)
Public finance [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	24
Notional Amount of Derivatives	1,543.5
Derivative assets (liabilities), at fair value, net	(9.5)
Total Assumed [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	244
Notional Amount of Derivatives	1,037.9
Derivative assets (liabilities), at fair value, net	(9.5)
Assumed structured finance [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	235
Notional Amount of Derivatives	899.4
Derivative assets (liabilities), at fair value, net	(8.2)
Assumed public finance [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	9
Notional Amount of Derivatives	138.5
Derivative assets (liabilities), at fair value, net	(1.3)
Financial Guaranty VIE derivative liabilities [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	0	[2]
Notional Amount of Derivatives	0	[2]
Derivative assets (liabilities), at fair value, net	(19.5)	[2]
Radian Group Consolidated [Member]
Derivatives, Fair Value [Line Items]
Number of Credit Risk Derivatives Held	373
Notional Amount of Derivatives	36,516.7		41,600.0
Derivative assets (liabilities), at fair value, net	$ (108.8)		$ (697.4)

[1] Represents NIMS derivative assets related to consolidated NIMS VIEs. Also includes common stock warrants. Because none of these investments represent financial guaranty contracts that we issued, they cannot become liabilities, and therefore, do not represent additional par exposure.

[2] Represents the fair value of an interest rate swap included in the consolidation of one of our financial guaranty transactions. The notional amount of the interest rate swap does not represent additional par exposure, and therefore, is excluded from this table. See Note 5 for information on our maximum exposure to loss from our consolidated financial guaranty transactions.