Note 7 - Cash, Cash Equivalents and Investments (Tables)

3 Months Ended

Mar. 31, 2014

Fair Value Disclosures [Abstract]

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

	Estimated Fair Market Value as of
	March 31, 2014		December 31, 2013
Cash, cash equivalents and investments:
Cash	$	62,857	$	62,625
Money market funds		26,028		35,588
U.S. treasuries and government agency bonds		139,750		128,126
Auction-rate securities backed by student-loan notes		9,843		9,860
Total cash, cash equivalents and investments	$	238,478	$	236,199

Schedule of Other Current Assets [Table Text Block]

Reported as:	March 31, 2014		December 31, 2013
Cash and cash equivalents	$	88,885	$	101,213
Short-term investments		139,750		125,126
Long-term investments		9,843		9,860
Total cash, cash equivalents and investments	$	238,478	$	236,199

Investments Classified by Contractual Maturity Date [Table Text Block]

	March 31, 2014		December 31, 2013
Due in less than 1 year	$	89,651	$	95,509
Due in 1 - 5 years		50,099		29,617
Due in greater than 5 years		9,843		9,860
	$	149,593	$	134,986

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

	As of March 31, 2014
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	26,028	$	-	$	-		$	26,028	$	-
U.S. treasuries and government agency bonds		139,743		32		(25	)		139,750		34,000
Auction-rate securities backed by student-loan notes		10,220		-		(377	)		9,843		9,843
	$	175,991	$	32	$	(402	)	$	175,621	$	43,843

	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

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

	Fair Value Measurement at March 31, 2014
			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	$	26,028	$	26,028	$	-	$	-
U.S. treasuries and government agency bonds		139,750		-		139,750		-
Auction-rate securities backed by student-loan notes		9,843		-		-		9,843
	$	175,621	$	26,028	$	139,750	$	9,843

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

Balance at January 1, 2014	$	9,860
Sales and settlement at par		-
Change in unrealized loss included in other comprehensive income		(17	)
Ending balance at March 31, 2014	$	9,843

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

	March 31, 2014			December 31, 2013
Time-to-liquidity (months)		24			24
Expected return		2.7%			2.5%
Discount rate	3.6%	-	8.4%	3.3%	-	8.1%