Stock-Based Compensation (Tables)

9 Months Ended

Sep. 26, 2015

Assumptions Used to Estimate The Fair Value of The Performance-based Stock Options and Restricted Stock Units

The assumptions used to estimate the fair value of the performance-based stock options and restricted stock units granted during the first nine months of 2015 under the Monte Carlo Simulation model are as follows:

	Nine Months Ended
	September 26, 2015	September 27, 2014
Risk-free interest rate	0.95% - 1.48%		—
Expected dividend yield	0%		—
Expected option life	4 years		—
Expected volatility	44.5%		—
Weighted-average expected volatility	44.5%		—

Fair Value of Options Granted

For stock options granted during the nine months ended September 26, 2015 and September 27, 2014 valued using the Black-Scholes option-pricing model, we used the following assumptions:

	Nine Months Ended
	September 26, 2015	September 27, 2014
Risk-free interest rate	0.80% - 1.09%	0.95% - 1.32%
Expected dividend yield	0%	0%
Expected option life	3 years	3 - 4 years
Expected volatility	42.3% - 48.5%	42.5% - 45.4%
Weighted-average expected volatility	43.1%	42.6%

Summary of Stock Option Activity

A summary of stock option activity and weighted-average exercise prices for the nine months ended September 26, 2015 follows:

	Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value as of September 26, 2015
Outstanding at January 1, 2015		898,429		$	44.40
Granted		465,005			58.57
Forfeited		(97,251	)		55.06
Exercised		(66,786	)		33.11
Outstanding at September 26, 2015		1,199,397		$	50.04		4.6	$	1,961
Options exercisable at September 26, 2015		573,736		$	42.49		3.1	$	1,961

Summary of Restricted Stock Activity

The following table summarizes the restricted stock and restricted stock unit activity and weighted average grant-date fair values for the nine months ended September 26, 2015:

	Shares			Weighted-Average Grant Date Fair Value
Non-vested at January 1, 2015		13,955		$	43.57
Granted		16,892			43.62
Forfeited		(1,397	)		46.16
Vested		(13,349	)		42.99
Non-vested at September 26, 2015		16,101		$	43.88