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

6 Months Ended

Jun. 30, 2014

Fair Value Disclosures [Abstract]

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

	Estimated Fair Market Value as of
	June 30, 2014		December 31, 2013
Cash, cash equivalents and investments:
Cash	$	76,899	$	62,625
Money market funds		30,964		35,588
U.S. treasuries and government agency bonds		133,012		128,126
Auction-rate securities backed by student-loan notes		9,848		9,860
Total cash, cash equivalents and investments	$	250,723	$	236,199

Schedule of Other Current Assets [Table Text Block]

Reported as:	June 30, 2014		December 31, 2013
Cash and cash equivalents	$	107,863	$	101,213
Short-term investments		133,012		125,126
Long-term investments		9,848		9,860
Total cash, cash equivalents and investments	$	250,723	$	236,199

Investments Classified by Contractual Maturity Date [Table Text Block]

	June 30, 2014		December 31, 2013
Due in less than 1 year	$	86,825	$	95,509
Due in 1 - 5 years		46,187		29,617
Due in greater than 5 years		9,848		9,860
	$	142,860	$	134,986

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

	As of June 30, 2014
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	30,964	$	-	$	-		$	30,964	$	-
U.S. treasuries and government agency bonds		132,996		31		(15	)		133,012		39,607
Auction-rate securities backed by student-loan notes		10,220		-		(372	)		9,848		9,848
	$	174,180	$	31	$	(387	)	$	173,824	$	49,455

	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 June 30, 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	$	30,964	$	30,964	$	-	$	-
U.S. treasuries and government agency bonds		133,012		-		133,012		-
Auction-rate securities backed by student-loan notes		9,848		-		-		9,848
	$	173,824	$	30,964	$	133,012	$	9,848

	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
Change in unrealized loss included in other comprehensive income		(17	)
Ending balance at March 31, 2014		9,843
Change in unrealized loss included in other comprehensive income		5
Ending balance at June 30, 2014	$	9,848

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

	June 30, 2014			December 31, 2013
Time-to-liquidity (months)		24			24
Expected return		2.7%			2.5%
Discount rate	3.5%	-	8.3%	3.3%	-	8.1%