Stock-Based Compensation

12 Months Ended

Dec. 31, 2018

18. Stock-Based Compensation

During the year ended December 31, 2018, we granted performance share units (which we refer to as “PSUs”) covering up to 0.3 million shares of common stock, assuming maximum level of performance, with a grant date fair value of $28.10 per share that are subject to both service and performance vesting conditions. The quantity of shares that will vest under the PSUs range from 0% to 250% of a targeted number of shares for each participant and will be determined based on an achievement of a three-year pre-tax income performance goal. During the year ended December 31, 2018, we also granted restricted stock units (which we refer to as “RSUs”) covering 0.3 million shares of common stock with a grant date fair value of $30.43 per share that vest over a one to three-year period. As of December 31, 2018, we had no remaining unvested restricted stock awards (which we refer to as “RSAs”) outstanding.

The following table summarizes the activity of our RSU, RSA, and PSU for the years ended December 31, 2018, 2017 and 2016 (in thousands):


	Year Ended December 31,
	2018			2017			2016
	Shares		Weighted average per share grant date fair value	Shares		Weighted average per share grant date fair value	Shares		Weighted average per share grant date fair value
Outstanding, beginning of year	834	$	18.16	852	$	15.81	696	$	18.18
Granted	592		29.86	460		21.64	514		14.28
Vested	(491)		18.02	(452)		17.19	(297)		18.65
Forfeited	(89)		22.44	(26)		19.63	(61)		16.05
Outstanding, end of year	846	$	25.14	834	$	18.16	852	$	15.81

A summary of our outstanding RSUs and PSUs, assuming maximum level of performance, are as follows (in thousands, except years):


	As of December 31, 2018
Unvested units		846
Unrecognized compensation cost	$	9,472
Period to recognize compensation cost		1.8 years

During the years ended December 31, 2018, 2017 and 2016, the Company recognized stock-based compensation expense of $13.7 million, $9.5 million and $6.7 million, respectively, which is generally included in selling, general, and administrative on the Consolidated Statements of Operations.