Note 6 - Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2019

Notes Tables

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

	June 30, 2019
(in thousands)	Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. municipal securities	$	6,651	$	12	$	(1	)	$	6,662
Corporate debt securities		26,519		105		(11	)		26,613
U.S. government agency securities		12,997		2		(12	)		12,987
Certificates of deposit/time deposits		1,975		16		(2	)		1,989
U.S. treasury securities		1,993		1		-			1,994
Total marketable securities	$	50,135	$	136	$	(26	)	$	50,245

	December 31, 2018
(in thousands)	Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. municipal securities	$	17,509	$	1	$	(33	)	$	17,477
Corporate debt securities		31,769		-		(96	)		31,673
U.S. government agency securities		16,843		-		(88	)		16,755
Certificates of deposit/time deposits		4,208		-		(25	)		4,183
Total marketable securities	$	70,329	$	1	$	(242	)	$	70,088

Investments Classified by Contractual Maturity Date [Table Text Block]

	June 30,
(in thousands)	2019
Due in one year or less	$	35,867
Due after one year through five years		14,268
Total marketable securities	$	50,135