Note 4 - Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Fair Value Measurement at December 31, 2015
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	31,640	$	31,640	$	-	$	-
Certificates of deposit		21,574		-		21,574		-
U.S. treasuries and government agency bonds		123,532		-		123,532		-
Auction-rate securities backed by student-loan notes		5,361		-		-		5,361
Mutual funds under deferred compensation plan		8,279		8,279		-		-
Total	$	190,386	$	39,919	$	145,106	$	5,361

	Fair Value Measurement at December 31, 2014
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	60,078	$	60,078	$	-	$	-
Certificates of deposit		22,778		-		22,778		-
U.S. treasuries and government agency bonds		89,674		-		89,674		-
Auction-rate securities backed by student-loan notes		5,389		-		-		5,389
Mutual funds under deferred compensation plan		2,236		2,236		-		-
Total	$	180,155	$	62,314	$	112,452	$	5,389
Liabilities:
Contingent consideration	$	2,507	$	-	$	-	$	2,507
Total	$	2,507	$	-	$	-	$	2,507

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		(4,650	)
Change in unrealized loss included in other comprehensive income		179
Ending balance at December 31, 2014		5,389
Change in unrealized loss included in other comprehensive income		(28	)
Ending balance at December 31, 2015	$	5,361

Fair Value Inputs, Assets, Quantitative Information [Table Text Block]

	December 31,
	2015			2014
Time-to-liquidity (months)		24			24
Expected return		2.9%			2.9%
Discount rate	4.3%	-	7.3%	4.0%	-	7.0%

Fair Value Inputs, Liabilities, Quantitative Information [Table Text Block]

	December 31, 2014
Projected revenue (in millions)	$2.1	-	$3.8
Discount rate		9.0%
Probability of occurrence	20%	-	50%