Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2016

For stock options granted during the six months ended June 30, 2016 and June 27, 2015 valued using the Black-Scholes option valuation model, we used the following assumptions:


	Six Months Ended
	June 30, 2016			June 27, 2015
Risk-free interest rate		1.06% - 1.21	%		0.80% - 1.09	%
Expected dividend yield		0	%		0	%
Expected option life		4 years			3 years
Expected volatility		46.7% - 47	%		42.3% - 48.5	%
Weighted-average expected volatility		46.7	%		43.2	%

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 six months ended June 27, 2015 and valued under the Monte Carlo Simulation model were as follows:


	Six Months Ended
	June 30, 2016		June 27, 2015
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	%

Summary of Stock Option Activity

A summary of stock option activity and weighted-average exercise prices during the six months ended June 30, 2016 follows:


	Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value as of June 30, 2016
Outstanding at January 1, 2016		1,178,585		$	48.14
Granted		169,740			33.04
Forfeited		(178,089	)		44.65
Exercised		(104,957	)		17.65
Unearned performance-based options		(23,328	)		59.97

Outstanding at June 30, 2016		1,041,951		$	49.08		4.7	$	553,354

Options exercisable at June 30, 2016		558,556		$	50.64		3.6	$	211,118

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 30, 2016:


	Shares			Weighted-Average Grant Date Fair Value
Non-vested at January 1, 2016		15,916		$	43.47
Granted		150,660			33.14
Forfeited		(5,394	)		33.05
Vested		(13,247	)		42.79
Unearned performance-based awards		(677	)		53.03

Non-vested at June 30, 2016		147,258		$	33.33