Note 12 - Interest and Other Income, Net - Interest and Other Income Components (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest income	$ 1,563	$ 1,327	$ 3,024	$ 2,591
Amortization of premium on available-for-sale investments	(374)	(498)	(808)	(1,005)
Gain on deferred compensation plan investments	419	533	233	1,266
Foreign currency exchange gain (loss)	614	(125)	214	(234)
Other	10		10
Total	$ 2,232	$ 1,237	$ 2,673	$ 2,618

Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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