Note 4 - Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

Available-for-sale Securities [Table Text Block]

		March 31, 2021							December 31, 2020
	Fair Value Level1	Adjusted Cost		Gross Unrealized Losses			Fair Value		Adjusted Cost		Gross Unrealized Losses			Fair Value
Money market funds	Level 1	$	22,553	$	—		$	22,553	$	21,042	$	—		$	21,042
Time deposits	Level 2		5,000		—			5,000		5,458		—			5,458
Government and municipal debt securities	Level 2		18,455		(7	)		18,448		30,280		(5	)		30,275
Corporate debt securities	Level 2		20,231		(11	)		20,220		11,621		(6	)		11,615
Total investments		$	66,239	$	(18	)	$	66,221	$	68,401	$	(11	)	$	68,390