Note 4 - Derivative Instruments Change in Fair Value of Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	$ 628,395	$ (558,712)	$ 99,958
Net Premiums Earned On Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	41,700	47,100	55,700
Financial Guaranty Credit Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	598,000	(583,200)	118,000
Financial Guaranty VIE Derivative Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	(10,700)	(14,500)	0
NIMS [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	(1,600)	(900)	(6,200)
Mortgage Insurance Domestic And International CDS[Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	0	0	(4,800)
Put Options On CPS[Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	0	(6,100)	(56,200)
Other Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	1,000	(1,100)	(6,500)
Radian Group Consolidated [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative instruments	$ 628,400	$ (558,700)	$ 100,000