Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Summary of Stock-Based Compensation Grants

The following table summarizes the Company’s stock-based compensation grants for the six months ended June 30, 2019:

	Stock Awards Granted		Weighted-Average  Grant Price Per Share
Time-based restricted stock units		26,325	$	77.53
Performance-based restricted stock units (a)		80,104	$	47.89
Stock appreciation rights		24,536	$	77.70

(a) Includes 32,462 of target performance-based restricted stock unit awards granted during the six months ended June 30, 2019, and adjustments of 27,154, 14,900 and 5,588 to grants due to the actual performance level achieved for restricted stock and restricted stock units awarded in 2016, 2017, and 2018, respectively.

Summary of Assumptions Used to Estimate Fair Value of Each SAR

The fair value of each SAR is estimated on the date of grant using a Black-Scholes option-pricing formula. For SARs issued in the six months ended June 30, 2019 and 2018 the data and assumptions shown in the following table were used:

	Six Months Ended June 30, 2019			Six Months Ended June 30, 2018
Weighted-average fair value of grants	$	29.56		$	22.09
Dividend yield		0	%		0	%
Average risk-free interest rate		2.5	%		2.7	%
Expected term (years)		5			5
Expected volatility		39.1	%		40.4	%

Summary of Stock-Based Compensation Expense

The following table summarizes the Company’s stock-based compensation expense (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Stock appreciation rights	$	203	$	56	$	498	$	259
Time-based restricted stock and restricted stock units		1,306		578		2,455		1,400
Performance-based restricted stock and restricted stock units		569		666		1,883		1,919
Employee stock purchase plan		47		45		82		67
Total stock-based compensation	$	2,125	$	1,345	$	4,918	$	3,645