Note 2 - Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

Notes Tables

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

	Three Months Ended March 31,
	2017		2016
Cost of revenue	$	358	$	434
Research and development		3,498		3,698
Selling, general and administrative		7,806		4,847
Total	$	11,662	$	8,979

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Time-Based RSUs			Weighted-Average Grant Date Fair Value Per Share		PSUs and MPSUs			Weighted-Average Grant Date Fair Value Per Share		MSUs		Weighted-Average Grant Date Fair Value Per Share		Total			Weighted-Average Grant Date Fair Value Per Share
Outstanding at January 1, 2017		366		$	51.35		2,284		$	43.24		1,620	$	23.57		4,270		$	36.47
Granted		47		$	89.37		527	(1)	$	62.86		-	$	-		574		$	65.02
Released		(61	)	$	46.83		(360	)	$	43.71		-	$	-		(421	)	$	44.16
Forfeited		(5	)	$	60.85		(3	)	$	52.30		-	$	-		(8	)	$	57.51
Outstanding at March 31, 2017		347		$	57.12		2,448		$	47.38		1,620	$	23.57		4,415		$	39.41

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]

	Three Months Ended March 31,
	2017			2016
Expected term (years)		0.5			0.5
Expected volatility		23.4	%		29.7	%
Risk-free interest rate		0.7	%		0.4	%
Dividend yield		0.9	%		1.4	%