Note 3 - Derivative Instruments Derivatives (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012 derivative		Dec. 31, 2011
NIMS related and other [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	0	[1]
Derivative, Notional Amount	$ 0	[1]
Derivative Assets (Liabilities), at Fair Value, Net	1.8	[1]
Corporate collateralized debt obligations (CDO's)[Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	47
Derivative, Notional Amount	18,391.4
Derivative Assets (Liabilities), at Fair Value, Net	1.1
Non Corporate CDOS and other derivative transactions[Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	48
Derivative, Notional Amount	5,120.2
Derivative Assets (Liabilities), at Fair Value, Net	(170.3)
Trust Preferred Securities (TruPs) [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	13
Derivative, Notional Amount	1,122.6
Derivative Assets (Liabilities), at Fair Value, Net	(11.3)
CDOS of commercial mortgage backed securities (CMBS)[Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	4
Derivative, Notional Amount	1,831.0
Derivative Assets (Liabilities), at Fair Value, Net	(79.9)
Structured finance [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	8
Derivative, Notional Amount	709.0
Derivative Assets (Liabilities), at Fair Value, Net	(40.3)
Public finance [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	23
Derivative, Notional Amount	1,457.6
Derivative Assets (Liabilities), at Fair Value, Net	(38.8)
Total Assumed [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	43
Derivative, Notional Amount	378.6
Derivative Assets (Liabilities), at Fair Value, Net	(14.0)
Assumed structured finance [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	35
Derivative, Notional Amount	249.3
Derivative Assets (Liabilities), at Fair Value, Net	(12.9)
Assumed public finance [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	8
Derivative, Notional Amount	129.3
Derivative Assets (Liabilities), at Fair Value, Net	(1.1)
Financial Guaranty VIE derivative liabilities [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	1	[2]
Derivative, Notional Amount	75.9	[2]
Derivative Assets (Liabilities), at Fair Value, Net	(71.1)	[2]
Radian Group Consolidated [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	139
Derivative, Notional Amount	23,966.1		36,500.0
Derivative Assets (Liabilities), at Fair Value, Net	$ (252.5)		$ (108.8)

[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 a CDS included in a VIE which we consolidate relating to the Terminated TruPs CDOs. The assets in the VIE represent the only funds available to pay the CDS Counterparty for amounts due under the contract; therefore, the notional exposure presented for the CDS is limited to the current trust assets. See Notes 1 and 5 for information on the underlying reference securities and on our maximum exposure to loss from this consolidated financial guaranty transaction.