Note 13 - Selected Statements of Income Data (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Interest and Other Income [Table Text Block]

	Year ended December 31,
	2018			2019			2020
Interest income	$	4,499		$	4,220		$	3,291
Loss on available-for-sale marketable securities, net		(67	)		(28	)		(6	)
Amortization of premium on available-for-sale marketable securities, net		(773	)		(554	)		(444	)
Foreign exchange gain (loss), net		(241	)		(347	)		443
Total	$	3,418		$	3,291		$	3,284

Equity Securities without Readily Determinable Fair Value [Table Text Block]

Initial cost basis	$	1,806
Downward adjustments		(870	)
Total carrying value at the end of the period	$	936