Note 19 - Income Taxes - Difference Between US Federal Statutory Tax Rate and Company's Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. federal statutory tax rate	35.00%	35.00%	35.00%
Tax monetization			2.50%
State income tax, net of federal benefit	(0.20%)	0.60%	(0.70%)
Effect of foreign income tax, net	(14.10%)	(5.10%)	(4.90%)
Production tax credits	(8.30%)	(0.10%)	0.90%
Subpart F income	0.30%	1.30%	1.40%
Depletion			(1.10%)
Other, net	(1.30%)		0.80%
Effective tax rate	22.50%	(13.50%)	32.20%
Domestic Tax Authority [Member]
Valuation allowance	11.10%	(1.40%)	(1.70%)
Foreign Tax Authority [Member]
Valuation allowance		(43.80%)