Note 2 - Significant Accounting Policies (Details) (USD $)	12 Months Ended									12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Mortgage Insurance Segment	Dec. 31, 2010 Mortgage Insurance Segment	Dec. 31, 2009 Mortgage Insurance Segment	Dec. 31, 2011 Default To Claim Rate Assumptions Twelve Or More Missed Payments [Member]	Dec. 31, 2011 Default To Claim Rate Assumptions Two Missed Payments [Member]	Dec. 31, 2011 Default To Claim Rate Assumptions Three Missed Payments [Member]	Dec. 31, 2011 Financial Guaranty Segment	Dec. 31, 2010 Financial Guaranty Segment	Dec. 31, 2009 Financial Guaranty Segment	Dec. 31, 2009 Accounting Standards Update 2009-08	Dec. 31, 2011 Computer Equipment [Member]	Dec. 31, 2011 Leasehold Improvements [Member]
Losses and LAE Mortgage Insurance [Abstract]
Weighted Average Default To Claim Rate Assumption Net Of Denials And Rescissions	43.00%	40.00%		43.00%	40.00%
Default To Claim Rate Estimate Net Of Rescission And Denial Estimates For Insured Loans That Missed Two To Three Monthly Payments				19.00%
Default To Claim Estimate Net Of Rescission And Denial Estimates For Loans That Missed Twelve Or More Monthly Payments				52.00%
Number Of Payments Missed For Insured Loans							12	2	3
Percentage Of Defaults Related To Origination Years 2005 Through 2008				76.20%	78.30%
Under Our Master Insurance Policy Any Suit Or Action Arising From Any Right Of The Insured Under The Policy Must Be Commenced Within This Number Of Years After Such Right First Arose	2
Under Our Master Insurance Policy Any Suit Or Action Arising From Any Right Of Certain Other Policies Must Be Commenced Within This Number Of Years After Such Right First Arose	3
Fair Value Level III Assets and Liabilities [Abstract]
Total Level III Assets	4.90%
Total Level III Liabilities	100.00%
Deferred Policy Acquisition Costs Disclosures [Abstract]
Deferred Policy Acquisition Cost, Amortization Expense	$ 52,763,000	$ 53,469,000	$ 63,034,000	$ 36,100,000	$ 36,100,000	$ 27,600,000				$ 16,700,000	$ 17,400,000	$ 35,500,000
Net Par Outstanding Commuted in 2009												9,800,000,000
Write off of deferred policy acquisition costs as a result of the 2009 commutation												8,900,000
Deferred Policy Acquisition Costs, Additions				46,200,000	42,200,000
Investments [Abstract]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets													21,500,000
Company-Owned Life Insurance
Life Insurance, Corporate or Bank Owned, Amount	$ 73,700,000	$ 71,600,000
Property, Plant and Equipment, Useful Life, Maximum														3	7