Note 5 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability		$ (56,500,000)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%	35.00%
Deferred Income Tax Expense (Benefit), Excluding Effective Changes in Tax Rate		$ 8,000,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Excluding Changes in Tax Rate, Percent		40.10%
Unrecognized Tax Benefits		$ 407,000	$ 536,000
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions		129,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		322,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense		$ 11,000	$ 59,000
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%