Note 10 - Losses and Loss Adjustment Expense Mortgage Insurance Reserve for Losses and LAE Rollforward (Details) $ in Thousands		9 Months Ended			12 Months Ended
		Sep. 30, 2018 USD ($) incident	Sep. 30, 2017 USD ($)		Dec. 31, 2017 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Number of Natural Disasters | incident		2
Loss reserve [Roll Forward]
Balance at beginning of period		$ 507,588
Deduct paid claims and LAE related to [Abstract]
Balance at end of period		412,460			$ 507,588
Mortgage Insurance Segment
Loss reserve [Roll Forward]
Balance at beginning of period		507,588	$ 760,269		760,269
Less: Reinsurance recoverables	[1]	8,350	6,851		6,851
Balance at beginning of period, net of reinsurance recoverables		499,238	753,418		753,418
Add losses and LAE incurred in respect of default notices reported and unreported in [Abstract]
Incurred Losses and LAE Current year	[2]	100,047	145,798
Incurred Losses and LAE Prior years		(24,075)	(45,331)
Total incurred losses and LAE		75,972	100,467
Deduct paid claims and LAE related to [Abstract]
Paid Losses and LAE Current year	[2]	2,316	3,639
Paid losses and LAE Prior years		173,911	301,228
Total paid losses and LAE		176,227	304,867	[3]
Balance at end of period, net of reinsurance recoverables		398,983	549,018		499,238
Add: Reinsurance recoverables	[1]	9,997	7,470		8,350
Balance at end of period		$ 408,980	$ 556,488		507,588
Default To Claim Rate Detail [Abstract]
Default To Claim Rate Estimate, Gross, For New Defaults		8.50%	10.50%
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount		$ 5,900			10,400
Mortgage Insurance Segment | Pool Insurance Mortgage Insurance Product
Loss reserve [Roll Forward]
Balance at beginning of period	[4]	13,463
Less: Reinsurance recoverables	[5]	35
Add losses and LAE incurred in respect of default notices reported and unreported in [Abstract]
Incurred Losses and LAE Prior years			$ 14,200
Deduct paid claims and LAE related to [Abstract]
Add: Reinsurance recoverables	[5]	20			35
Balance at end of period	[4]	11,705			13,463
Mortgage Insurance Segment | Primary Mortgage Product
Loss reserve [Roll Forward]
Less: Reinsurance recoverables	[5]	8,315
Deduct paid claims and LAE related to [Abstract]
Add: Reinsurance recoverables	[5]	$ 9,977			$ 8,315
Default To Claim Rate Detail [Abstract]
Weighted Average Default To Claim Rate Assumption Net Of Denials Rescissions and Reinstatements		34.00%			31.00%
Weighted Average Default To Claim Rate Assumption Net Of Denials Rescissions and Reinstatements Excluding Defaults in FEMA Designated Areas		35.00%			38.00%
Default To Claim Rate Estimate, Gross, For Pre-Foreclosure Stage Defaults		68.00%
Gross Default To Claim Rate Estimate		75.00%
Mortgage Insurance Segment | Hurricanes Harvey and Irma [Member] | Primary Mortgage Product
Default To Claim Rate Detail [Abstract]
Default To Claim Rate Estimate, Gross, For New Defaults		3.00%
2013 Freddie Mac Agreement [Member] | Radian Guaranty Inc [Member] | Mortgage Insurance Segment
Deduct paid claims and LAE related to [Abstract]
Paid losses and LAE Prior years			$ 54,800

[1] Related to ceded losses recoverable, if any, on captive reinsurance transactions, the QSR Program and the Single Premium QSR Program. See Note 7 for additional information.

[2] Related to underlying defaulted loans with a most recent default notice dated in the year indicated. For example, if a loan had defaulted in a prior year, but then subsequently cured and later re-defaulted in the current year, that default would be considered a current year default.

[3] Includes the payment of $54.8 million made in connection with the scheduled final settlement of the Freddie Mac Agreement in the third quarter of 2017.

[4] Includes reinsurance recoverable of $20 thousand and $35 thousand as of September 30, 2018 and December 31, 2017, respectively.

[5] Represents ceded losses on captive reinsurance transactions, the QSR Program and the Single Premium QSR Program. These amounts are included in the reinsurance recoverables reported in other assets in our condensed consolidated balance sheets.