STOCK-BASED COMPENSATION

9 Months Ended

Sep. 30, 2021

Share-based Payment Arrangement [Abstract]

Total stock-based compensation cost charged to selling, general and administrative expenses for the three and nine months ended September 30, 2021 was $6.0 million and $12.8 million, respectively. Total stock-based compensation cost charged to selling, general and administrative expenses for the three and nine months ended September 30, 2020 was $6.7 million and $12.7 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation expense for the three and nine months ended September 30, 2021 was $1.3 million and $2.8 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation expense for the three and nine months ended September 30, 2020 was $1.7 million and $2.9 million, respectively.

Restricted Stock Awards

The following table summarizes information about restricted stock awards for the nine months ended September 30, 2021:


Restricted Stock	Number of Shares	Weighted Average Grant-Date Fair Value
Balance at January 1, 2021	493,879	$	59.74
Granted	174,225	93.95
Vested	(181,651)	57.68
Forfeited	(39,091)	61.75
Balance at September 30, 2021	447,362	73.72

As of September 30, 2021, there was $26.3 million of total unrecognized compensation cost arising from restricted stock awards. This cost is expected to be recognized over a weighted average period of 3.0 years. The total fair value of restricted stock vested during the three and nine months ended September 30, 2021 was $7.4 million and $16.3 million, respectively. The total fair value of restricted stock vested during the three and nine months ended September 30, 2020 was $3.1 million and $12.8 million, respectively.

Performance Stock Awards

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 targets currently based on revenue, Adjusted EBITDA, Adjusted EBITDA Margin, Adjusted Free Cash Flow, Return on Invested Capital and Total Recordable Incident Rate. In addition, performance stock awards include continued service conditions.

The following table summarizes information about performance stock awards for the nine months ended September 30, 2021:


Performance Stock	Number of Shares	Weighted Average Grant-Date Fair Value
Balance at January 1, 2021	254,449	$	61.75
Granted	134,931	92.92
Vested	(71,815)	62.27
Forfeited	(26,191)	64.47
Balance at September 30, 2021	291,374	75.81

As of September 30, 2021, there was $10.0 million of total unrecognized compensation cost arising from unvested performance stock awards deemed probable of vesting. No performance awards vested during the three months ended September 30, 2021 and September 30, 2020. The total fair value of performance awards vested during the nine months ended September 30, 2021 and September 30, 2020 was $6.4 million and $1.3 million, respectively.