Note 6 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%
Deferred Tax Liabilities, Net		$ 3,917
Deferred Tax Liabilities, Before Change in Enacted Tax Rate		6,200
Deferred Tax Assets, Operating Loss Carryforwards		276,239
Unrecognized Tax Benefits		0	$ 6,525
Unrecognized Tax Benefits, Interest on Income Taxes Expense			$ 0	$ 0
Domestic Tax Authority [Member]
Operating Loss Carryforwards		$ 1,100
Domestic Tax Authority [Member] | Earliest Tax Year [Member]
Open Tax Year		2014
Domestic Tax Authority [Member] | Latest Tax Year [Member]
Open Tax Year		2016
State and Local Jurisdiction [Member]
Operating Loss Carryforwards		$ 602,400
State and Local Jurisdiction [Member] | Earliest Tax Year [Member]
Open Tax Year		2013
Foreign Tax Authority [Member]
Operating Loss Carryforwards		$ 19,900
Operating Loss Carryforwards, Unlikely to be Utilized		$ 908,600
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%