Note 15 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Revaluation of Deferred Tax Asset, Decrease				$ 3,851
Reclassification of Existing AMT Tax Credits				$ 8,913
Budget Sequestration Rate				6.60%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ (703)	$ (703)	$ 3,851
Effective Income Tax Rate Reconciliation, Alternative Minimum Tax Sequestration, Amount	$ 569		569
Income Taxes Receivable, Current	5,087		5,087
Deferred Tax Assets, Valuation Allowance, Total	162		162	204
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount			$ (42)	65
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	64,818		64,818
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	42,512		42,512
Alternative Minimum Tax Credit [Member]
Tax Credit Carryforward, Reduction Amount				$ 569
Income Taxes Receivable, Current	$ 5,087		$ 5,087