Note 8 - Reserve for Premium Deficiency First Lien Portfolio (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
First Lien Portfolio Premium Excess [Line Items]
Number Of Months In Future At Which Current Default Rates Will Hold With Those Rates Observed At Prior Year End	12
Number Of Years Beyond The Next Twelve Months That It Will Take For Loan Defaults To Return To Normal Historical Levels	3
Mortgage Insurance Segment [Member] | Total First Lien Loans [Member]
First Lien Expected Losses Assumptions [Abstract]
Expected Paid Claim Rate In Our First Lien PDR	12.30%
Mortgage Insurance Segment [Member] | Performing Loans [Member]
First Lien Expected Losses Assumptions [Abstract]
Expected Paid Claim Rate In Our First Lien PDR	6.80%
Mortgage Insurance Segment [Member] | Nonperforming Loans [Member]
First Lien Expected Losses Assumptions [Abstract]
Expected Paid Claim Rate In Our First Lien PDR	42.40%
Percentage Change In Expected Gross Default To Claim Rate Used In Performing A Sensitivity Analysis On Our First Lien Portfolio	10.00%
Maximum Default To Claim Rate On Defaulted Loans And Pending Claims Used In Stressing Scenario	100.00%
Expected Default To Claim Rate On Our First Lien Portfolio Of Defaulted Loans When Shocked By Ten Percent	45.70%
Amount By Which Expected Losses Would Increase Based On A Ten Percent Change In Expected Default To Claim Rate On First Lien Defaulted Loans	$ 189
Mortgage Insurance Segment [Member] | First Lien Portfolio for PDR Disclosure [Member]
First Lien Portfolio Premium Excess [Line Items]
Net Present Value Of Expected Premiums	2,627	2,806
Net Present Value Of Expected Losses And Expenses	(4,629)	(4,537)
Reserve For Premiums And Losses Established Net Of Reinsurance Recoverables	3,045	3,276
Net projected premium excess	$ 1,043	$ 1,545
Liability for Future Policy Benefit by Product Segment, Interest Rate	2.60%	2.40%