Note 7 - Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal statutory tax provision		$ (26)	$ 4,534	$ 6,798
State tax provision		(110)	283	465
Stock compensation expense	[1]	(944)	45	677
Tax credits		(2,769)	(4,000)	(4,166)
Foreign tax, net		1,641	2,852	3,111
Tax Law Changes		3,247
Other		224	139	130
Tax provision		$ 1,263	$ 3,853	$ 7,015

[1] Due to the adoption of ASU 2016-09, excess tax benefits from share-based award activity for the year ended December 31, 2016 are reflected as a reduction of the provision for income taxes, whereas they previously were recognized in equity. See Note 1 "Business and Significant Accounting Policies" in the Notes to the Consolidated Financial Statements for additional information related to this adoption.