Note 9 - Income Taxes - Reconciliation of Income Tax (Benefit) Expense (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax provision at statutory rate – federal	21.00%	35.00%	35.00%
U.S. tax reform toll charge	0.00%	562.20%	0.00%
Tax rate change deferred revaluation	0.00%	(63.30%)	0.00%
Tax provision at effective state and local rates	(9.60%)	23.90%	(21.10%)
Foreign tax rate differential	(12.80%)	(158.30%)	(216.40%)
Subpart F income	22.70%	0.00%	0.00%
Nondeductible expenses	0.20%	6.50%	51.70%
Uncertain tax provisions	(0.40%)	1.20%	0.20%
Valuation allowance	(11.90%)	2.80%	22.10%
Prior period adjustments	(3.20%)	11.20%	(37.70%)
Stock compensation	(0.80%)	(9.50%)	0.00%
Tax credits	(0.10%)	(7.30%)	0.00%
Other	0.00%	0.00%	(5.90%)
Total effective income tax rate	5.10%	404.40%	(172.10%)