STOCK-BASED COMPENSATION

Stock-Based Compensation

In 2010, the Company adopted an equity incentive plan (the "2010 Plan"), which provides for awards of up to 6,000,000 shares of common stock (subject to certain anti-dilution adjustments) in the form of (i) stock options, (ii) stock appreciation rights, (iii) restricted stock, (iv) restricted stock units, and (v) certain other stock-based awards. The Company ceased issuing

(17) STOCK-BASED COMPENSATION (Continued)

stock options in 2008, and all awards issued to date under the 2010 Plan have been in the form of restricted stock awards and performance stock awards as described below.

As of December 31, 2018 and 2017, the Company had the following types of stock-based compensation awards outstanding under the 2010 Plan: restricted stock awards and performance stock awards. The restricted stock awards generally vest over three to five years subject to continued employment. The performance stock awards vest depending on the satisfaction of certain performance criteria and continued service conditions as described below.

Total stock-based compensation cost charged to selling, general and administrative expenses for the years ended December 31, 2018, 2017 and 2016 was $16.8 million, $13.1 million and $10.5 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $3.2 million, $3.7 million and $2.8 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Restricted Stock Awards

The following information relates to restricted stock awards that have been granted to employees and directors under the Company's 2010 Plan. The restricted stock awards are not transferable until vested and the restrictions generally lapse upon the achievement of continued employment over a three-to-five-year period or service as a director until the following annual meeting of shareholders. The fair value of each restricted stock grant is based on the closing price of the Company's common stock on the date of grant and is amortized to expense over its vesting period.

The following table summarizes information about restricted stock awards for the year ended December 31, 2018:



Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Unvested at January 1, 2018	604,933		$	54.23
Granted	327,466		55.02
Vested	(198,673	)	54.22
Forfeited	(76,486	)	54.00
Unvested at December 31, 2018	657,240		$	54.65

As of December 31, 2018, there was $24.9 million of total unrecognized compensation cost arising from restricted stock awards. This cost is expected to be recognized over a weighted average period of 2.6 years. The total fair value of restricted stock vested during 2018, 2017 and 2016 was $10.8 million, $7.3 million and $8.3 million, respectively.

Performance Stock Awards

The following information relates to performance stock awards that have been granted to employees. The compensation committee of the Company's board of directors established two-year performance targets which could potentially be achieved in the year granted or one year thereafter. Performance stock awards are subject to performance criteria established by the compensation committee of the Company's board of directors. The vesting of the performance stock awards is based on achieving such targets typically based on revenue, Adjusted EBITDA margin, free cash flow and a measure of workplace safety. In addition, performance stock awards include continued service conditions.

The fair value of each performance stock award is based on the closing price of the Company's common stock on the date of grant and is amortized to expense over the service period if achievement of performance measures is then considered probable.

(17) STOCK-BASED COMPENSATION (Continued)

The following table summarizes information about performance stock awards for the year ended December 31, 2018:



Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Unvested at January 1, 2018	190,129		$	55.63
Granted	171,584		55.71
Vested	(21,416	)	54.82
Forfeited	(126,807	)	53.59
Unvested at December 31, 2018	213,490		$	55.71

As of December 31, 2018, there was $3.2 million of total unrecognized compensation cost arising from non-vested compensation related to performance stock awards then deemed probable of vesting under the Company's 2010 Plan. The total fair value of performance awards vested during 2018, 2017 and 2016 was $1.2 million, $3.0 million and $1.0 million, respectively.