Note 4 - Fair Value Measurement - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Marketable securities (Note 3)		$ 77,469	$ 82,664
Investment in other company	[1]	936
Foreign exchange contracts		77
Fair Value, Inputs, Level 1 [Member]
Investment in other company	[1]
Foreign exchange contracts
Fair Value, Inputs, Level 2 [Member]
Investment in other company	[1]
Foreign exchange contracts		77
Fair Value, Inputs, Level 3 [Member]
Investment in other company	[1]	936
Foreign exchange contracts
Certificates of Deposits [Member]
Marketable securities (Note 3)		747	747
Certificates of Deposits [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable securities (Note 3)
Certificates of Deposits [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable securities (Note 3)		747	747
Certificates of Deposits [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable securities (Note 3)
Government Bonds [Member]
Marketable securities (Note 3)		496	495
Government Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable securities (Note 3)
Government Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable securities (Note 3)		496	495
Government Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable securities (Note 3)
Corporate Bonds [Member]
Marketable securities (Note 3)		76,226	81,422
Corporate Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Marketable securities (Note 3)
Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Marketable securities (Note 3)		76,226	81,422
Corporate Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Marketable securities (Note 3)

[1] Non-marketable equity securities remeasured during the year ended December 31, 2018.