Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Summary of Stock-Based Compensation Expense

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

	Year Ended December 31,
	2021		2020		2019
Time-based restricted stock and restricted stock units	$	2,892	$	3,219	$	3,676
Performance-based restricted stock and restricted stock units		4,681		2,881		2,399
Stock appreciation rights		485		648		662
Employee stock purchase plan		381		383		193
Total stock-based compensation	$	8,439	$	7,131	$	6,930

Summary of Assumptions Used to Estimate Fair Value of Each SAR

For SARs issued in the years ended December 31, 2021, December 31, 2020 and December 31, 2019, respectively, the assumptions shown in the following table were used:

	Year Ended December 31,
	2021			2020			2019
Dividend yield		0	%		0	%		0	%
Average risk-free interest rate		0.6	%		1.3	%		2.5	%
Expected term (years)		5			5			5
Expected volatility		58.7	%		38.3	%		39.1	%

SAR Activity

SAR activity under the Plan and all predecessor stock incentive plans is as follows:

	SARs			Weighted-Average Grant Price Per Share		Weighted-Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value as of December 31, 2021
Outstanding at December 31, 2018		476,952		$	9.63
Granted		49,072		$	38.85
Exercised		(217,528	)	$	6.95
Canceled		(4,458	)	$	38.85
Outstanding at December 31, 2019		304,038		$	15.79
Granted		43,830		$	50.39
Exercised		(54,592	)	$	9.41
Canceled		—		$	—
Outstanding at December 31, 2020		293,276		$	22.15
Granted		15,029		$	104.56
Exercised		(102,562	)	$	9.45
Canceled		(4,745	)	$	61.66
Outstanding at December 31, 2021		200,998		$	33.86		5.3	$	20,335,938
Vested at December 31, 2021		161,244		$	25.58		5.3	$	17,647,952
Exercisable at December 31, 2021		161,244		$	25.58		5.3	$	17,647,952

Time-Based Restricted Stock and Time-Based Restricted Stock Units [Member]

Restricted Stock Activity

Time-based restricted stock and restricted stock unit activity under the Plan and all predecessor stock incentive plans is as follows:

	Time-based Restricted Stock and Restricted Stock Unit			Weighted-Average Grant Price Per Share
Nonvested at December 31, 2018		311,096		$	21.34
Granted		71,300		$	38.12
Vested		(162,650	)	$	18.67
Forfeited		(1,280	)	$	31.17
Nonvested at December 31, 2019		218,466		$	28.75
Granted		54,406		$	53.97
Vested		(111,036	)	$	30.94
Forfeited		(1,114	)	$	40.34
Nonvested at December 31, 2020		160,722		$	35.68
Granted		33,703		$	100.50
Vested		(78,081	)	$	37.81
Forfeited		(4,798	)	$	66.00
Nonvested at December 31, 2021		111,546		$	52.91

Performance-Based Restricted Stock and Performance-Based Restricted Stock Units [Member]

Restricted Stock Activity

Performance-based restricted stock activity under the Plan is as follows:

	Performance-based Restricted Stock and Performance-based Restricted Stock Units			Weighted-Average Grant Price Per Share
Nonvested at December 31, 2018		182,412		$	18.43
Granted		164,270		$	23.82
Vested		(222,004	)	$	15.55
Forfeited		(1,022	)	$	29.23
Nonvested at December 31, 2019		123,656		$	30.67
Granted		78,404		$	39.60
Vested		(128,762	)	$	28.87
Forfeited		(728	)	$	41.12
Nonvested at December 31, 2020		72,570		$	43.42
Granted		36,522		$	86.26
Vested		(45,051	)	$	39.41
Forfeited		(6,273	)	$	65.30
Nonvested at December 31, 2021		57,768		$	71.21