Note 10 - Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

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

	Fair Value Measurement at June 30, 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	$	34,689	$	34,689	$	-	$	-
Certificates of deposit		23,093		-		23,093		-
U.S. treasuries and government agency bonds		127,073		-		127,073		-
Auction-rate securities backed by student-loan notes		5,375		-		-		5,375
Mutual funds under deferred compensation plan		4,846		4,846		-		-
Total	$	195,076	$	39,535	$	150,166	$	5,375
Liabilities:
Contingent consideration	$	2,507	$	-	$	-	$	2,507
Total	$	2,507	$	-	$	-	$	2,507

	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, 2015	$	5,389
Change in unrealized loss included in other comprehensive income		(14	)
Ending balance at June 30, 2015	$	5,375

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

	June 30,			December 31,
	2015			2014
Time-to-liquidity (months)		24			24
Expected return		2.7%			2.9%
Discount rate	3.9%	-	6.9%	4.0%	-	7.0%