Note 8 - Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Debt Securities, Available-for-sale [Table Text Block]

	December 31, 2021
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government agency securities	$	2,500	$	-	$	(12	)	$	2,488
Corporate debt securities		9,303		-		(44	)		9,259
U.S. municipal securities		12,549		-		(70	)		12,479
Commercial paper		-		-		-			-
Certificates of deposit/time deposits		1,687		7		-			1,694
Total marketable securities	$	26,039	$	7	$	(126	)	$	25,920

Debt Securities, Held-to-maturity [Table Text Block]

	December 31, 2020
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government agency securities	$	18,500	$	6	$	(10	)	$	18,496
Corporate debt securities		42,048		211		(11	)		42,248
U.S. municipal securities		25,003		83		(2	)		25,084
Commercial paper		2,499		-		-			2,499
Certificates of deposit/time deposits		5,395		93		-			5,488
Total marketable securities	$	93,445	$	393	$	(23	)	$	93,815

Investments Classified by Contractual Maturity Date [Table Text Block]

	December 31,
(in thousands)	2021
Due in one year or less	$	11,580
Due after one year through five years		14,340
Total marketable securities	$	25,920