Note 1 - Condensed Consolidated Financial Statements - Business Overview and Significant Accounting Policies Business Overview and Significant Accounting Policies(Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended	12 Months Ended
		Mar. 31, 2018 USD ($) segment $ / shares shares	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Aug. 09, 2017 USD ($)
Business Overview [Abstract]
Number of Operating Segments | segment		2
Mortgage Insurance [Abstract]
Restructuring and other exit costs		$ 551	$ 0
Restructuring and other exit costs - cash payments		$ 500
Mortgage Insurance Segment
Mortgage Insurance [Abstract]
Private Mortgage Insurance Protects Lenders For Loans Made With Less Than This Maximum Down Payment Percentage		20.00%
Private Mortgage Insurance Protects Lenders For Refinancings Made to Home Buyers With Less Than This Maximum Equity-Ownership Percentage		20.00%
Mortgage and Real Estate Services Segment [Member]
Mortgage Insurance [Abstract]
Restructuring and other exit costs	[1]	$ 525	0
Total Primary Insurance Mortgage Insurance Products [Member] | Mortgage Insurance Segment
Mortgage Insurance [Abstract]
Risk In Force		$ 52,200,000
Third Quarter 2017 Repurchase Program [Member]
Mortgage Insurance [Abstract]
Stock Repurchase Program, Authorized Amount						$ 50,000
Stock Repurchased During Period, Shares | shares		531,013
Accelerated Share Repurchases, Final Price Paid Per Share | $ / shares		$ 18.84
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 40,000
Scenario, Forecast [Member]
Mortgage Insurance [Abstract]
Restructuring and other exit costs				$ 3,100	$ 3,700
Restructuring and other exit costs - cash payments				$ 2,500
Scenario, Forecast [Member] | Asset Impairment Charges [Member]
Mortgage Insurance [Abstract]
Restructuring and other exit costs					600
Scenario, Forecast [Member] | Employee Severance and Benefit Costs [Member]
Mortgage Insurance [Abstract]
Restructuring and other exit costs					900
Scenario, Forecast [Member] | Facility and Lease Termination Costs [Member]
Mortgage Insurance [Abstract]
Restructuring and other exit costs					1,600
Scenario, Forecast [Member] | Contract Termination and Other Restructuring Costs [Member]
Mortgage Insurance [Abstract]
Restructuring and other exit costs					$ 600
Accounting Standards Update 2016-01 [Member]
Basis of Presentation and Business Overview [Line Items]
Increase in Invested Assets		2,300
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Basis of Presentation and Business Overview [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		224	0
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Basis of Presentation and Business Overview [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		2,061	0
Accounting Standards Update 2018-02 [Member] | AOCI Attributable to Parent [Member]
Basis of Presentation and Business Overview [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		2,724	0
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member]
Basis of Presentation and Business Overview [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		(2,724)	$ 0
Unrealized Loss Related to Equity Securities [Member] | Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Basis of Presentation and Business Overview [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		(224)
Practical Expedient to Measure Certain Other Investments Using the NAV [Member] | Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Basis of Presentation and Business Overview [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 2,300

[1] Primarily includes employee severance and related benefit costs. Does not include impairment of long-lived assets, which is not a component of adjusted pretax operating income.