Note 2 - Cash, Cash Equivalents and Investments (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2012

Dec. 31, 2013

Fair Value Disclosures [Abstract]

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

	Estimated Fair Market Value as of
	December 31, 2013		December 31, 2012
Cash, cash equivalents and investments:
Cash	$	62,625	$	59,145
Money market funds		35,588		15,959
U.S. treasuries and government agency bonds		128,126		85,521
Auction-rate securities backed by student-loan notes		9,860		11,755
Total cash, cash equivalents and investments	$	236,199	$	172,380

Schedule of Other Current Assets [Table Text Block]

Reported as:	December 31, 2013		December 31, 2012
Cash and cash equivalents	$	101,213	$	75,104
Short-term investments		125,126		85,521
Long-term investments		9,860		11,755
Total cash, cash equivalents and investments	$	236,199	$	172,380

Investments Classified by Contractual Maturity Date [Table Text Block]

	December 31, 2013		December 31, 2012
Due in less than 1 year	$	95,509	$	52,880
Due in 1 - 5 years		29,617		32,641
Due in greater than 5 years		9,860		11,755
	$	134,986	$	97,276

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

	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
	$	173,931	$	26	$	(383	)	$	173,574	$	52,740

	As of December 31, 2012
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	15,959	$	-	$	-		$	15,959	$	-
U.S. treasuries and government agency bonds		85,483		45		(7	)		85,521		14,121
Auction-rate securities backed by student-loan notes		12,245		-		(490	)		11,755		11,755
	$	113,687	$	45	$	(497	)	$	113,235	$	25,876

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

	Fair Value Measurement at December 31, 2013
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		Level 1		Level 2		Level 3
Money market funds	$	35,588	$	35,588	$	-	$	-
U.S. treasuries and government agency bonds		128,126		-		128,126		-
Auction-rate securities backed by student-loan notes		9,860		-		-		9,860
	$	173,574	$	35,588	$	128,126	$	9,860

	Fair Value Measurement at December 31, 2012
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		Level 1		Level 2		Level 3
Money market funds	$	15,959	$	15,959	$	-	$	-
U.S. treasuries and government agency bonds		85,521		-		85,521		-
Auction-rate securities backed by student-loan notes		11,755		-		-		11,755
	$	113,235	$	15,959	$	85,521	$	11,755

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

Beginning balance at January 1, 2012	$	13,675
Sales and settlement at par		(2,100	)
Realized gain included in interest and other income, net		40
Change in unrealized loss included in other comprehensive income		140
Balance at December 31, 2012		11,755
Sales and settlement at par		(2,025	)
Change in unrealized loss included in other comprehensive income		130
Ending balance at December 31, 2013	$	9,860

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

	At December 31, 2013			At December 31, 2012
Time-to-liquidity (months)		24			24
Expected return		2.5%			1.8%
Discount rate	3.3%	-	8.1%	2.5%	-	7.3%