Note 3 - Derivative Instruments Derivatives (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 derivative		Dec. 31, 2012
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	1,578	[1]
Corporate collateralized debt obligations (CDO's)[Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	25
Derivative, Notional Amount	9,670,390
Derivative Assets (Liabilities), at Fair Value, Net	(9,960)
Non Corporate CDOS and other derivative transactions[Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	45
Derivative, Notional Amount	4,912,598
Derivative Assets (Liabilities), at Fair Value, Net	(335,560)
Trust Preferred Securities (TruPs) [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	13
Derivative, Notional Amount	1,071,305
Derivative Assets (Liabilities), at Fair Value, Net	(42,899)
CDOS of commercial mortgage backed securities (CMBS)[Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	4
Derivative, Notional Amount	1,831,000
Derivative Assets (Liabilities), at Fair Value, Net	(95,936)
Structured finance [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	5
Derivative, Notional Amount	566,116
Derivative Assets (Liabilities), at Fair Value, Net	(133,603)
Public finance [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	23
Derivative, Notional Amount	1,444,177
Derivative Assets (Liabilities), at Fair Value, Net	(63,122)
Total Assumed [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	39
Derivative, Notional Amount	297,942
Derivative Assets (Liabilities), at Fair Value, Net	(13,775)
Assumed structured finance [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	32
Derivative, Notional Amount	187,454
Derivative Assets (Liabilities), at Fair Value, Net	(13,157)
Assumed public finance [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	7
Derivative, Notional Amount	110,488
Derivative Assets (Liabilities), at Fair Value, Net	(618)
Financial Guaranty VIE derivative liabilities [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	1	[2]
Derivative, Notional Amount	76,792	[2]
Derivative Assets (Liabilities), at Fair Value, Net	(66,752)	[2]
Radian Group Consolidated [Member]
Derivative [Line Items]
Number of Credit Risk Derivatives Held	110
Derivative, Notional Amount	14,957,722		19,200,000
Derivative Assets (Liabilities), at Fair Value, Net	$ (424,469)		$ (253,264)

[1] Represents NIMS derivative assets related to consolidated NIMS VIEs. Because 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 that we have consolidated. See Note 5 for more information on this transaction, the underlying reference securities and our maximum exposure to loss from this consolidated financial guaranty transaction. 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.