Note 3 - Cash, Cash Equivalents and Investments (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure Text Block Supplement [Abstract]

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

	As of December 31,
	2014		2013
Cash, cash equivalents and investments:
Cash	$	66,188	$	62,625
Money market funds		60,078		35,588
Certificates of deposit		22,778		-
U.S. treasuries and government agency bonds		89,674		128,126
Auction-rate securities backed by student-loan notes		5,389		9,860
Total	$	244,107	$	236,199

Schedule of Other Current Assets [Table Text Block]

	As of December 31,
	2014		2013
Reported as:
Cash and cash equivalents	$	126,266	$	101,213
Short-term investments		112,452		125,126
Long-term investments		5,389		9,860
Total	$	244,107	$	236,199

Investments Classified by Contractual Maturity Date [Table Text Block]

	As of December 31,
	2014		2013
Due in less than 1 year	$	91,335	$	95,509
Due in 1 - 5 years		21,117		29,617
Due in greater than 5 years		5,389		9,860
Total	$	117,841	$	134,986

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

	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

	As of December 31, 2013
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	35,588	$	-	$	-		$	35,588	$	-
U.S. treasuries and government agency bonds		128,123		26		(23	)		128,126		42,880
Auction-rate securities backed by student-loan notes		10,220		-		(360	)		9,860		9,860
Total	$	173,931	$	26	$	(383	)	$	173,574	$	52,740