Stock-Based Compensation Expense (Tables)

9 Months Ended

Oct. 02, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity for the nine-month period ended October 2, 2016:

	Shares (in thousands)		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2015	6,644		$	28.27
Granted	1,751		34.10
Exercised	(1,224	)	18.87
Forfeited or expired	(141	)	36.97
Outstanding as of October 2, 2016	7,030		$	31.18	7.4	$	152,398
Exercisable as of October 2, 2016	2,700		$	23.01	5.6	$	80,589
Options vested or expected to vest as of October 2, 2016 (1)	6,391		$	30.59	7.2	$	142,335

 (1) In addition to the vested options, the Company expects a portion of the unvested options to vest at some point in the future. Options expected to vest are calculated by applying an estimated forfeiture rate to the unvested options.

Weighted-Average Assumptions Used in Estimating Fair Values of Stock Options Granted

The fair values of stock options granted in each period presented were estimated using the following weighted-average assumptions:

	Three-months Ended				Nine-months Ended
	October 2, 2016		October 4, 2015		October 2, 2016		October 4, 2015
Risk-free rate	1.7	%	2.1	%	1.7	%	2.1	%
Expected dividend yield	0.84	%	1.25	%	0.84	%	1.25	%
Expected volatility	41	%	40	%	41	%	40	%
Expected term (in years)	5.5		5.4		5.5		5.4

Nonvested Restricted Stock Shares Activity

The following table summarizes the Company's restricted stock activity for the nine-month period ended October 2, 2016:

	Shares (in thousands)	Weighted-Average Grant Fair Value		Aggregate Intrinsic Value (in thousands)(1)
Nonvested as of December 31, 2015	20	$	34.05
Granted	—	—
Vested	—	—
Forfeited or expired	—	—
Nonvested as of October 2, 2016	20	$	34.05	$	1,057

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

The following table presents the stock-based compensation expense by caption for each period presented on the Consolidated Statements of Operations (in thousands):

	Three-months Ended				Nine-months Ended
	October 2, 2016		October 4, 2015		October 2, 2016		October 4, 2015
Cost of revenue	$	273	$	351	$	795	$	1,167
Research, development, and engineering	1,366		1,130		4,942		4,097
Selling, general, and administrative	2,983		2,906		10,146		10,273
Discontinued operations	—		1,106		—		1,533
	$	4,622	$	5,493	$	15,883	$	17,070