Note 8 - Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

Jun. 30, 2012

Fair Value Disclosures [Abstract]

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

	Estimated Fair Market Value as of
	June 30, 2013		December 31, 2012
Cash, cash equivalents and investments
Cash in banks	$	85,994	$	59,145
Money market funds		15,741		15,959
US treasuries and US government agency bonds		87,884		85,521
Auction-rate securities backed by student-loan notes		11,698		11,755
Total cash, cash equivalents and investments	$	201,317	$	172,380

Schedule of Other Current Assets [Table Text Block]

Reported as:	June 30, 2013		December 31, 2012
Cash and cash equivalents	$	101,735	$	75,104
Short-term investments		87,884		85,521
Long-term investments		11,698		11,755
Total cash, cash equivalents and investments	$	201,317	$	172,380

Investments Classified by Contractual Maturity Date [Table Text Block]

	June 30, 2013		December 31, 2012
Due in less than 1 year	$	65,670	$	52,880
Due in 1 - 5 years		22,214		32,641
Due in greater than 5 years		11,698		11,755
	$	99,582	$	97,276

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

	Fair Value Measurements at June 30, 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	$	15,741	$	15,741	$	-	$	-
US treasuries and US government agency bonds		87,884		-		87,884		-
Long-term available-for-sale auction-rate securities		11,698		-		-		11,698
	$	115,323	$	15,741	$	87,884	$	11,698

	Fair Value Measurements 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	$	-	$	-
US treasuries and US government agency bonds		85,521		-		85,521		-
Long-term available-for-sale auction-rate securities		11,755		-		-		11,755
	$	113,235	$	15,959	$	85,521	$	11,755

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

	As of June 30, 2013
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	15,741	$	-	$	-		$	15,741	$	-
US treasuries and US government agency bonds		87,868		35		(19	)		87,884		22,425
Auction-rate securities backed by student-loan notes		12,220		-		(522	)		11,698		11,698
	$	115,829	$	35	$	(541	)	$	115,323	$	34,123

	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	$	-
US treasuries and US 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, Unobservable Input Reconciliation [Table Text Block]

Beginning balance at January 1, 2013	$	11,755
Sales and settlement at par		(25	)
Unrealized loss included in other comprehensive income		(15	)
Ending balance at March 31, 2013		11,715
Unrealized loss included in other comprehensive income		(17	)
Ending balance at June 30, 2013	$	11,698

Schedule of Discounted Cash Flow Model Values [Table Text Block]

	At June 30, 2013	At December 31, 2012
Time-to-liquidity (months)	24	24
Expected return (based on the requisite treasury rate, plus a contractual penalty rate)	2.3%	1.8%
Discount rate (based on the requisite LIBOR, the cost of debt and a liquidity risk premium)	3.1%-7.9%, depending on the credit-rating of the security	2.5%-7.3%, depending on the credit-rating of the security