Note 7 - Reinsurance Reinsurance Transactions (Details) - Reinsurer Concentration Risk [Member] - Radian Guaranty - USD ($) $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended		36 Months Ended
		Dec. 31, 2017	Oct. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
2016 Single Premium QSR Program
Ceded Credit Risk [Line Items]
Percent of Ceded Risk								35.00%
Risk In Force				$ 6,400,000	$ 4,300,000	$ 6,400,000	$ 4,300,000
2018 Single Premium QSR Program
Ceded Credit Risk [Line Items]
Percent of Ceded Risk		65.00%
Risk In Force				1,600,000		1,600,000
Ceded Premiums Written			$ 335,000
Single Premium QSR Program
Ceded Credit Risk [Line Items]
Ceded Premiums Written	[1]			20,920	13,248	64,818	36,064
Ceded Premiums Earned	[1]			11,181	6,771	32,718	18,941
Ceding commissions written				8,070	5,156	24,571	14,002
Ceding Commissions Earned	[2]			5,635	3,536	16,546	9,721
Ceded losses				1,060	406	2,973	1,443
QSR Program
Ceded Credit Risk [Line Items]
Ceded Premiums Written	[1]			3,174	4,621	10,621	15,137
Ceded Premiums Earned	[1]			4,632	6,826	15,502	22,064
Ceding commissions written				918	1,323	3,058	4,328
Ceding Commissions Earned	[2]			2,738	2,925	9,182	10,198
Ceded losses				131	257	383	517
First Lien Mortgage Insurance Products [Member] | QSR Program
Ceded Credit Risk [Line Items]
Risk In Force				$ 1,000,000	$ 1,300,000	$ 1,000,000	$ 1,300,000

[1] Net of profit commission.

[2] Includes amounts reported in policy acquisition costs and other operating expenses.