Stock-Based Awards (Tables)

6 Months Ended

Jun. 30, 2019

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

Summary of Unrecognized Stock-Based Compensation Expense and Average Remaining Vesting Period

A summary of unrecognized stock-based compensation expense and average remaining vesting period is as follows:


	June 30, 2019
	Unrecognized Stock- Based Compensation		Average Remaining Vesting Period (Years)
Employees and directors	$	21,078		2.16

Summary of Stock Options, Restricted Stock, Restricted Stock Unit and Performance Stock Unit Activity

A summary of stock-based compensation award activity during the three months ended June 30, 2019 is as follows:


	Stock Options		RSAs			RSUs		PRSUs
Balance at April 1, 2019		550,537		3,270,065			40,436		270,872	(1)
Granted		—		97,649			—		—
Exercised/vested		—		(105,319	)		—		—
Forfeitures		—		(31,142	)		—		—

Balance at June 30, 2019		550,537		3,231,253			40,436		270,872	(1)

(1)

Represents the target number of PRSUs granted and outstanding. The number of PRSUs that ultimately vest ranges from 0% to 200% of this amount. A Monte Carlo simulation was used to value these awards using the following assumptions for the Company and the peer group: (i) beginning

90-day

average stock prices; (ii) valuation date stock prices; (iii) historical stock price volatilities ranging from 22% to 42% (average 28%); (iv) correlation coefficients based upon the price data used to calculate the historical volatilities; (v) a risk free interest rate of 2.56%; and (vi) an expected dividend yield of 0%.