Note 7 - Taxes on Income - Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statutory Federal income tax rate	34.00%	34.00%	34.00%
State and local income taxes, net of Federal income tax benefit	1.90%	1.60%	2.20%
Effect of change in unrecognized tax benefit		(0.10%)
Untaxed foreign income	(5.10%)	(6.00%)	(3.30%)
Non-deductible share-based employee compensation expense	1.20%	1.30%	1.60%
Excess tax benefit from stock compensation	(4.40%)
Federal tax credits	(0.80%)
Other items	(0.40%)	0.10%	0.80%
Effective income tax rate	26.40%	30.90%	35.30%