Note 7 - Income Taxes - Income Tax Rate Reconciliation (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statutory Federal income tax rate	21.00%	21.00%	21.00%	21.00%
State and local income taxes, net of Federal income tax benefit	4.00%	3.80%	4.00%	4.10%
Taxes attributable to foreign income	(8.60%)	(6.80%)	(6.00%)	(5.80%)
GILTI tax	2.90%	3.70%	2.20%	3.70%
Contingent liability adjustments	(1.90%)	(2.70%)	(0.80%)	(1.90%)
Compensation related	0.30%	1.60%	0.20%	1.40%
Non-deductible acquisition expense		1.90%		1.80%
Federal tax credits	(0.70%)		(0.70%)	(0.50%)
Other	(1.70%)	(6.60%)	(0.50%)	(2.70%)
Effective income tax rate	15.30%	15.90%	19.40%	21.10%