Note 8 - Cash, Cash Equivalents and Investments (Tables)

9 Months Ended

Sep. 30, 2016

Notes Tables

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

	September 30,		December 31,
	2016		2015
Cash, cash equivalents and investments:
Cash	$	62,218	$	58,217
Money market funds		47,261		31,640
Certificates of deposit		7,495		21,574
Corporate debt securities		20,665		-
U.S. treasuries and government agency bonds		121,424		123,532
Auction-rate securities backed by student-loan notes		5,382		5,361
Total	$	264,445	$	240,324

	September 30,		December 31,
	2016		2015
Reported as:
Cash and cash equivalents	$	109,479	$	90,860
Short-term investments		149,584		144,103
Long-term investments		5,382		5,361
Total	$	264,445	$	240,324

Investments Classified by Contractual Maturity Date [Table Text Block]

	September 30,		December 31,
	2016		2015
Due in less than 1 year	$	112,135	$	110,898
Due in 1 - 5 years		37,449		33,205
Due in greater than 5 years		5,382		5,361
Total	$	154,966	$	149,464

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

	September 30, 2016
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	47,261	$	-	$	-		$	47,261	$	-
Certificates of deposit		7,495		-		-			7,495		-
Corporate debt securities		20,703		4		(42	)		20,665		17,894
U.S. treasuries and government agency bonds		121,383		48		(7	)		121,424		26,037
Auction-rate securities backed by student-loan notes		5,570		-		(188	)		5,382		5,382
Total	$	202,412	$	52	$	(237	)	$	202,227	$	49,313

	December 31, 2015
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	31,640	$	-	$	-		$	31,640	$	-
Certificates of deposit		21,574		-		-			21,574		-
U.S. treasuries and government agency bonds		123,698		4		(170	)		123,532		110,720
Auction-rate securities backed by student-loan notes		5,570		-		(209	)		5,361		5,361
Total	$	182,482	$	4	$	(379	)	$	182,107	$	116,081