Note 4 - Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2014

Investments Schedule [Abstract]

Held-to-maturity Securities [Table Text Block]

	March 31, 2014
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government agency securities	$	24,476	$	1	$	(63	)	$	24,414
Corporate debt securities		37,314		30		(76	)		37,268
Commercial paper		1,996		-		(15	)		1,981
U.S. municipal securities		36,949		60		(10	)		36,999
Certificates of deposit/time deposits		4,940		8		(2	)		4,946
Total marketable securities	$	105,675	$	99	$	(166	)	$	105,608

	December 31, 2013
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government agency securities	$	21,713	$	2	$	(22	)	$	21,693
Corporate debt securities		29,480		30		(20	)		29,490
U.S. municipal securities		44,474		49		(22	)		44,501
Certificates of deposit/time deposits		4,695		5		(8	)		4,692
Total marketable securities	$	100,362	$	86	$	(72	)	$	100,376

Investments Classified by Contractual Maturity Date [Table Text Block]

(in thousands)	March 31, 2014
Due in one year or less	$	34,360
Due after one year through five years		71,315
Total marketable securities	$	105,675