Note 6 - Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2015

Notes Tables

Held-to-maturity Securities [Table Text Block]

	December 31, 2014
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. municipal securities	$	30,004	$	32	$	(18	)	$	30,018
Corporate debt securities		29,316		7		(79	)		29,244
U.S. government agency securities		20,048		-		(71	)		19,977
Certificates of deposit/time deposits		5,656		5		(15	)		5,646
Total marketable securities	$	85,024	$	44	$	(183	)	$	84,885

	June 30, 2015
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. municipal securities	$	32,661	$	20	$	(49	)	$	32,632
Corporate debt securities		25,932		5		(31	)		25,906
U.S. government agency securities		19,857		9		(23	)		19,843
Certificates of deposit/time deposits		5,656		12		-			5,668
Commercial paper		1,566		-		(1	)		1,565
Total marketable securities	$	85,672	$	46	$	(104	)	$	85,614

Investments Classified by Contractual Maturity Date [Table Text Block]

	June 30,
(in thousands)	2015
Due in one year or less	$	31,190
Due after one year through five years		54,482
Total marketable securities	$	85,672