Note 9 - Cash, Cash Equivalents and Investments (Tables)

9 Months Ended

Sep. 30, 2015

Disclosure Text Block Supplement [Abstract]

Fair Value, by Balance Sheet Grouping [Table Text Block]

	September 30,		December 31,
	2015		2014
Cash, cash equivalents and investments:
Cash	$	45,481	$	66,188
Money market funds		31,135		60,078
Certificates of deposit		22,008		22,778
U.S. treasuries and government agency bonds		131,039		89,674
Auction-rate securities backed by student-loan notes		5,364		5,389
Total	$	235,027	$	244,107

	September 30,		December 31,
Reported as:	2015		2014
Cash and cash equivalents	$	76,616	$	126,266
Short-term investments		153,047		112,452
Long-term investments		5,364		5,389
Total	$	235,027	$	244,107

Investments Classified by Contractual Maturity Date [Table Text Block]

	September 30,		December 31,
	2015		2014
Due in less than 1 year	$	120,745	$	91,335
Due in 1 - 5 years		32,302		21,117
Due in greater than 5 years		5,364		5,389
Total	$	158,411	$	117,841

Unrealized Gain (Loss) on Investments [Table Text Block]

	As of September 30, 2015
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	31,135	$	-	$	-		$	31,135	$	-
Certificates of deposit		22,008		-		-			22,008		-
U.S. treasuries and government agency bonds		130,978		64		(3	)		131,039		23,640
Auction-rate securities backed by student-loan notes		5,570		-		(206	)		5,364		5,364
Total	$	189,691	$	64	$	(209	)	$	189,546	$	29,004

	As of December 31, 2014
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	60,078	$	-	$	-		$	60,078	$	-
Certificates of deposit		22,778		-		-			22,778		-
U.S. treasuries and government agency bonds		89,689		14		(29	)		89,674		35,062
Auction-rate securities backed by student-loan notes		5,570		-		(181	)		5,389		5,389
Total	$	178,115	$	14	$	(210	)	$	177,919	$	40,451