Note 7 - Taxes on Income (Details Textual) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	34.00%	34.00%
Income Tax Expense (Benefit), Total	$ 5,000	$ 4,420	$ 9,760	$ 5,260
Tax Adjustments, Settlements, and Unusual Provisions	4,000		4,000
Net Discrete Tax Adjustment, Tax Act			3,300
Net Discrete Tax Adjustment, Other Miscellaneous Discrete Items			700
Accumulated Foreign Earnings and Profits Tax Rate, Liquid Assets		15.50%
Accumulated Foreign Earnings and Profits Tax Rate, Unremitted Foreign E&P		8.00%
Additional Deferred Tax Expense		$ 900
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total		100	100	100
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations		100	100	$ 100
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	100	100	100
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit		$ 100
Domestic Tax Authority [Member] | Earliest Tax Year [Member]
Open Tax Year		2015
State and Local Jurisdiction [Member] | Earliest Tax Year [Member]
Open Tax Year		2011
Other Noncurrent Liabilities [Member]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 500	$ 600	$ 500