Note 8 - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Tax at statutory federal income tax rate	34.00%	34.00%	34.00%
Increases (reductions) in taxes resulting from:
State income taxes, net of federal benefit	0.80%	0.40%	1.20%
Change in valuation allowance	0.90%	32.80%	(0.30%)
Domestic manufacturing deduction	(1.80%)	(3.50%)	(2.30%)
Capitalized acquisition costs
Effect of foreign operations	(2.30%)	(7.00%)	(8.50%)
Foreign dividend income
Tax-exempt interest
Changes in unrecognized tax benefits	(2.60%)		0.90%
Stock option compensation	2.90%	3.00%	1.80%
Research credit	(4.70%)	(4.30%)	(5.70%)
Other, including provision to return adjustments	6.30%	(0.20%)	0.70%
Effective income tax rate	33.50%	55.60%	21.80%