Stock-Based Compensation Expense (Tables)

6 Months Ended

Jul. 05, 2015

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

The following table summarizes the Company’s stock option activity for the six-month period ended July 5, 2015:



	Shares (in thousands)		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2014	6,812		$	23.26
Granted	1,427		41.36
Exercised	(1,280	)	16.76
Forfeited or expired	(43	)	8.68
Outstanding as of July 5, 2015	6,916		$	28.14	7.4	$	136,975
Exercisable as of July 5, 2015	2,533		$	16.74	5.6	$	79,074
Options vested or expected to vest as of July 5, 2015 (1)	6,140		$	26.97	7.2	$	128,812

(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				Six-months Ended
	July 5, 2015		June 29, 2014		July 5, 2015		June 29, 2014
Risk-free rate	2.1	%	2.7	%	2.1	%	2.7	%
Expected dividend yield	1.25	%	—	%	1.25	%	—	%
Expected volatility	40	%	41	%	40	%	41	%
Expected term (in years)	5.4		5.4		5.4		5.4

Nonvested Restricted Stock Shares Activity

The following table summarizes the Company's restricted stock award activity:



	Shares (in thousands)	Weighted-Average Exercise Price		Aggregate Intrinsic Value (in thousands)
Nonvested as of December 31, 2014	20	$	34.05
Granted	—	—
Vested	—	—
Forfeited or expired	—	—
Nonvested as of July 5, 2015	20	$	34.05	$	278

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

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



	Three-months Ended				Six-months Ended
	July 5, 2015		June 29, 2014		July 5, 2015		June 29, 2014
Cost of revenue	$	349	$	286	$	816	$	613
Research, development, and engineering	1,153		949		2,967		1,967
Selling, general, and administrative	2,985		2,473		7,367		4,825
Discontinued operations	144		248		427		555
	$	4,631	$	3,956	$	11,577	$	7,960

Upon the sale of the Company's Surface Inspection Systems Division to AMETEK, Inc., completed on July 6, 2015, as more fully described in Note 16 to the Consolidated Financial Statements, the Company accelerated the vesting of stock options, with respect to 171,000 underlying shares, resulting in an additional $1,105,000 of stock option expense in the third quarter of 2015.