Stock-Based Compensation (Tables)

6 Months Ended

Jun. 27, 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 six months of 2015 under the Monte Carlo Simulation model are as follows:

	Six Months Ended
	June 27, 2015			June 28, 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 six months ended June 27, 2015 and June 28, 2014 valued using the Black-Scholes option-pricing model, we used the following assumptions:

	Six Months Ended
	June 27, 2015			June 28, 2014
Risk-free interest rate		0.80% - 1.09	%		1.18% - 1.32	%
Expected dividend yield		0	%		0	%
Expected option life		3 years			4 years
Expected volatility		42.3% - 48.5	%		42.5% - 44.1	%
Weighted-average expected volatility		43.2	%		42.5	%

Summary of Stock Option Activity

A summary of stock option activity and weighted-average exercise prices for the six months ended June 27, 2015 follows:

	Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value as of June 27, 2015
Outstanding at January 1, 2015		898,429		$	44.40
Granted		437,053			59.60
Forfeited		(64,883	)		57.08
Exercised		(62,786	)		33.44
Outstanding at June 27, 2015		1,207,813		$	50.04		4.6	$	5,262
Options exercisable at June 27, 2015		580,998		$	42.49		3.3	$	4,919

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 six months ended June 27, 2015:

	Shares			Weighted-Average Grant Date Fair Value
Non-vested at January 1, 2015		13,955		$	43.57
Granted		16,892			46.98
Forfeited		(1,397	)		59.97
Vested		(13,343	)		42.99
Non-vested at June 27, 2015		16,107		$	45.85