Note 9 - Reinsurance Reinsurance Text (Details) (USD $)	12 Months Ended											1 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Reinsurance Premiums for Insurance Companies, by Product Segment [Domain]	Dec. 31, 2010 Reinsurance Premiums for Insurance Companies, by Product Segment [Domain]	Dec. 31, 2009 Reinsurance Premiums for Insurance Companies, by Product Segment [Domain]	Dec. 31, 2011 Reinsurance Premiums for Insurance Companies [Member]	Dec. 31, 2010 Reinsurance Premiums for Insurance Companies [Member]	Dec. 31, 2009 Reinsurance Premiums for Insurance Companies [Member]		Dec. 31, 2009 Commuted or Ceded [Member]	Jan. 24, 2012 January 2012 Assured Guaranty Reinsurance Commutation [Member]	Jan. 24, 2012 January 2012 Assured Guaranty Ceded Public Finance Transaction [Member]	Jan. 24, 2012 January 2012 Assured Guaranty Ceded Public Finance Transaction [Member] Commuted or Ceded [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount				$ 756,025,000	$ 825,733,000	$ 825,901,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies				(38,740,000)	(94,497,000)	(139,626,000)
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Assumed from Other Companies				32,337,000	29,063,000	45,749,000
Prepaid Reinsurance Premiums	800,000	1,000,000
Net Par Outstanding Commuted in 2009											9,800,000,000
Assumed Reinsurance Exposure Commuted In January 2012												13,800,000,000	1,800,000,000	1,800,000,000
Premiums Written, Net, Consolidated [Abstract]
Direct Premiums Written	755,758,000	788,321,000	790,052,000				755,758,000	788,321,000	790,052,000
Assumed Premiums Written	11,162,000	6,585,000	207,074,000				11,162,000	6,585,000	207,074,000	[1]	185,600,000
Ceded Premiums Written	(37,349,000)	(89,855,000)	(139,130,000)				(37,349,000)	(89,855,000)	(139,130,000)
Net premiums written	707,247,000	691,881,000	443,848,000				707,247,000	691,881,000	443,848,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Gross Amount				762,428,000	891,167,000	919,778,000
Premiums Earned, Net, Property and Casualty [Abstract]
Reinsurance Premiums for Insurance Companies, by Product Segment, Gross Amount				762,428,000	891,167,000	919,778,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Assumed from Other Companies				32,337,000	29,063,000	45,749,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies				(38,740,000)	(94,497,000)	(139,626,000)
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount				$ 756,025,000	$ 825,733,000	$ 825,901,000

[1] This amount includes a $185.6 million reduction related to the commutation of $9.8 billion in net par outstanding.