STOCK-BASED COMPENSATION AND EMPLOYEE BENEFIT PLANS

Stock-Based Compensation

In 2000, the Company adopted a stock incentive plan (the "2000 Plan"), which provided for awards in the form of incentive stock options, non-qualified stock options, restricted stock awards, performance stock awards and common stock awards. The 2000 Plan expired on April 15, 2010 and as of December 31, 2017, no options remained outstanding under that plan.

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 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, 2017 and 2016, the Company had the following types of stock-based compensation awards outstanding under the 2000 Plan and the 2010 Plan (collectively, the "Plans"): stock options, 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, 2017, 2016 and 2015 was $13.1 million, $10.5 million and $8.6 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $3.7 million, inclusive of $0.4 million from excess tax benefits on vested awards, $2.8 million and $2.3 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Restricted Stock Awards

The following information relates to restricted stock awards that have been granted to employees and directors under the Company's Plans. 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, 2017:



Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Unvested at January 1, 2017	510,041		$	52.65
Granted	307,455		55.93
Vested	(136,787	)	53.16
Forfeited	(75,776	)	52.46
Unvested at December 31, 2017	604,933		$	54.23

As of December 31, 2017, there was $24.1 million of total unrecognized compensation cost arising from restricted stock awards under the Company's Plans. This cost is expected to be recognized over a weighted average period of 2.8 years. The

(16) STOCK-BASED COMPENSATION AND EMPLOYEE BENEFIT PLANS (Continued)

total fair value of restricted stock vested during 2017, 2016 and 2015 was $7.3 million, $8.3 million and $6.9 million, respectively.

Performance Stock Awards

The following information relates to performance stock awards that have been granted to employees under the Company's Plans. 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 prior to or at the date of grant. The vesting of the performance stock awards is based on achieving such targets typically based on revenue, Adjusted EBITDA margin, free cash flow and Total Recordable Incident Rate. 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.

The following table summarizes information about performance stock awards for the year ended December 31, 2017:



Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Unvested at January 1, 2017	220,882		$	54.69
Granted	170,897		55.87
Vested	(53,096	)	55.60
Forfeited	(148,554	)	57.14
Unvested at December 31, 2017	190,129		$	55.63

As of December 31, 2017, there was $2.5 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 Plans. The total fair value of performance awards vested during 2017, 2016 and 2015 was $3.0 million, $1.0 million and $0.6 million, respectively.

Employee Benefit Plans

As of December 31, 2017, the Company has responsibility for a defined benefit plan that covered 12 active non-supervisory Canadian employees. For the years ended December 31, 2017 and 2016, net periodic pension costs were $0.4 million. For the year ended December 31, 2015, net periodic pension cost was $0.3 million. At December 31, 2017, the fair value of the Company's plan assets was $9.3 million. The fair value of $3.9 million of these plan assets was considered a Level 1 measure and the fair value of $5.4 million of these plan assets was considered a Level 2 measure, according to the fair value hierarchy. At December 31, 2016, the fair value of the Company's plan assets was $8.4 million. The fair value of $3.5 million of these plan assets was considered a Level 1 measure and the fair value of $4.9 million of these plan assets was considered a Level 2 measure, according to the fair value hierarchy. As of December 31, 2017 and 2016, the projected benefit obligation was $10.9 million and $9.9 million, respectively.