Note 2 - Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2016

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 September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Cost of revenue	$	403	$	303	$	1,217	$	829
Research and development		3,986		2,932		11,001		8,055
Selling, general and administrative		9,127		7,240		22,023		20,307
Total	$	13,516	$	10,475	$	34,241	$	29,191

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, 2016		499		$	40.75		1,933		$	38.99		1,800		$	23.57		4,232		$	32.64
Granted		129		$	62.54		1,288	(1)	$	41.07		-		$	-		1,417		$	43.03
Performance adjustment		-		$	-		(23	)(2)	$	40.05		-		$	-		(23	)	$	40.05
Released		(202	)	$	35.88		(649	)	$	29.86		-		$	-		(851	)	$	31.29
Forfeited		(23	)	$	43.83		(129	)	$	36.82		(180	)	$	23.57		(332	)	$	30.14
Outstanding at September 30, 2016		403		$	50.05		2,420		$	42.65		1,620		$	23.57		4,443		$	36.36

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
Expected term (years)		0.5			0.5			0.5			0.5
Expected volatility		27.5	%		24.8	%		28.6	%		30.3	%
Risk-free interest rate		0.5	%		0.2	%		0.4	%		0.2	%
Dividend yield		1.1	%		1.6	%		1.2	%		1.4	%