Note 15 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revaluation of Deferred Tax Asset, Decrease		$ 3,851
Reclassification of Existing AMT Tax Credits		$ 8,913
Budget Sequestration Rate		6.60%
Income Tax Expense (Benefit)		$ 2,584	$ 1,499	$ 10,200
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation			$ 47
Reclassification of Certain Deferred Income Tax Effects
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%	35.00%
Deferred Tax Assets, Valuation Allowance	$ 204	$ 204	$ 139
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		65	139
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax			9,380
Earliest Tax Year [Member]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2031
Latest Tax Year [Member]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2037
Domestic Tax Authority [Member]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	8,622	$ 8,622
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	78,068	78,068
State and Local Jurisdiction [Member]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	1,089	1,089
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	55,717	55,717
Retained Earnings [Member]
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation
Reclassification of Certain Deferred Income Tax Effects		425
AOCI Attributable to Parent [Member]
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation
Reclassification of Certain Deferred Income Tax Effects		(425)
Accounting Standards Update 2016-09 [Member]
Income Tax Expense (Benefit)		67
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member]
Reclassification of Certain Deferred Income Tax Effects	(425)
Accounting Standards Update 2018-02 [Member] | AOCI Attributable to Parent [Member]
Reclassification of Certain Deferred Income Tax Effects	$ (425)
Alternative Minimum Tax Credit [Member]
Tax Credit Carryforward, Reduction Amount		$ 569