Note 4 - Derivative Instruments Change in Fair Value of Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	$ (144,025)	$ 628,395	$ (558,712)
Net Premiums Earned On Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	28,693	41,753	47,123
Financial Guaranty Credit Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	(173,610)	597,969	(583,235)
Financial Guaranty VIE Derivative Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	1,189	(10,696)	(14,523)
NIMS [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	(297)	(631)	(1,937)
Put Options On CPS[Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	0	0	(6,140)
Radian Group Consolidated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	$ (144,025)	$ 628,395	$ (558,712)