On April 4, 2018, the Company’s board of directors approved the 2018 Omnibus Incentive Plan (the “2018 Omnibus Plan”), which was subsequently approved by the stockholders and became effective on May 31, 2018 (the “Effective Date”). The 2018 Omnibus Plan replaced the previous 2010 Omnibus Incentive Plan (the “Prior Plan”). The 2018 Omnibus Plan was amended on May 28, 2020 to increase the number of shares available for issuance.

The 2018 Omnibus Plan, as amended, allows the Company to grant 1,600,000 shares using stock options, stock appreciation rights, restricted stock, RSUs, performance units and PSAs, cash-based awards, and other stock-based awards to all key officers, key employees, and non-employee directors of the Company. Outstanding grants under the Prior Plan, totaling 90,742, remain subject to their terms and conditions, and no additional awards from the Prior Plan are to be made after the Effective Date. As of December 31, 2020, the Company had approximately 1,107,968 shares available to grant under the 2018 Omnibus Plan. CSRSUs have no impact on the shares available for grant under the 2018 Omnibus Plan and have no impact on the calculated shares used in earnings per share (“EPS”) calculations.

The total stock-based compensation expense for the years ended December 31, 2020, 2019, and 2018, the unrecognized compensation expense at December 31, 2020, and the weighted-average period to recognize the remaining unrecognized shares are as follows:

	Stock-Based Compensation Expense
	Recognized as of December 31,						Unrecognized
	2020		2019		2018		December 31, 2020		Weighted Average Period to Recognize (years)
Restricted Stock Units	$	11,895	$	10,644	$	7,410	$	10,777		1.7
Cash-Settled Restricted Stock Units		7,015		10,213		8,214		8,688		1.5
Non-Employee Director Awards		755		719		764		383		0.4
Performance Shares		4,905		4,455		3,193		2,229		1.5
Total	$	24,570	$	26,031	$	19,581	$	22,077

The assumptions of employment termination forfeiture rates used in the determination of fair value of stock awards during the 2020 calendar year were based on the Company’s historical average of actual forfeitures from the previous 10 years preceding the reporting period. The expected annualized forfeiture rates used during the 2020 calendar year varied from 0% to 17.75%, and the Company does not expect these termination rates to vary significantly in the future.

Option awards are granted with an exercise price equal to the market value of the Company’s common stock on the date of grant. All options outstanding as of December 31, 2020 have a 10-year contractual term. Options generally have a vesting term of three or four years. There were no option awards granted during 2020, 2019, and 2018.

	Number of Shares			Weighted Average Exercise Price		Aggregate Intrinsic Value
Outstanding at January 1, 2018		411,498		$	30.71
Exercised		(209,688	)	$	27.86
Granted		—		$	—
Forfeited/Expired		—		$	—
Outstanding at December 31, 2018		201,810		$	33.68
Exercised		(93,682	)	$	31.21
Granted		—		$	—
Forfeited/Expired		—		$	—
Outstanding at December 31, 2019		108,128		$	35.82
Exercised		(69,901	)	$	37.94
Granted		—		$	—
Forfeited/Expired		—		$	—
Outstanding at December 31, 2020		38,227		$	31.93	$	1,620,688
Vested plus expected to vest at December 31, 2020		38,227		$	31.93	$	1,620,688
Exercisable at December 31, 2020		38,227		$	31.93	$	1,620,688

The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $74.33 as of December 31, 2020. The total intrinsic value of options exercised was $5.1 million, $4.9 million, and $8.3 million for the years ended December 31, 2020, 2019, and 2018, respectively. All options were vested prior to December 31, 2018. As of December 31, 2020, the weighted-average remaining contractual term for options vested was 2.3 years and for exercisable options was 2.3 years.

Information regarding stock options outstanding as of December 31, 2020 is summarized below:

	OPTIONS OUTSTANDING						OPTIONS EXERCISABLE
Range of Exercise Prices	Number Outstanding As of December 31, 2020		Weighted Average Remaining Contractual Term		Weighted Average Exercise Price		Number Exercisable As of December 31, 2020		Weighted Average Exercise Price
$21.77 to $25.00		1,915		0.3	$	21.77		1,915	$	21.77
$25.01 to $27.00		6,332		1.2	$	25.66		6,332	$	25.66
$27.01 to $40.00		14,874		2.2	$	27.03		14,874	$	27.03
$40.01 to $41.00		15,106		3.2	$	40.68		15,106	$	40.68
$21.77 to $41.00		38,227		2.3	$	—		38,227	$	31.93

RSUs generally have a vesting term of three to four years. On vesting the employee is issued one share of stock for each RSU awarded. The fair value of shares vested was $14.1 million, $7.2 million, and $6.5 million for the years ended December 31, 2020, 2019, and 2018, respectively.

	Number of Shares			Weighted- Average Grant Date Fair Value		Aggregate Intrinsic Value
Non-vested RSUs at January 1, 2018		463,587		$	38.71
Granted		235,480		$	65.37
Vested		(169,279	)	$	38.66
Cancelled		(55,548	)	$	47.50
Non-vested RSUs at December 31, 2018		474,240		$	50.93
Granted		159,831		$	77.74
Vested		(164,913	)	$	43.82
Cancelled		(19,183	)	$	56.18
Non-vested RSUs at December 31, 2019		449,975		$	62.48
Granted		170,411		$	58.27
Vested		(258,307	)	$	54.73
Cancelled		(56,680	)	$	63.46
Non-vested RSUs at December 31, 2020		305,399		$	66.51	$	22,700,308
RSUs expected to vest in the future		279,087		$	66.69	$	20,744,537

The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $74.33 per share as of December 31, 2020.

CSRSUs generally have a vesting term of three to four years. A summary of the Company’s CSRSUs is presented below.

	Number of Shares			Weighted- Average Grant Date Fair Value		Aggregate Intrinsic Value
Non-vested CSRSUs at January 1, 2018		391,916		$	38.80
Granted		147,103		$	60.84
Vested		(147,759	)	$	38.71
Cancelled		(53,854	)	$	43.07
Non-vested CSRSUs at December 31, 2018		337,406		$	47.73
Granted		103,606		$	77.03
Vested		(123,395	)	$	44.61
Cancelled		(21,384	)	$	53.99
Non-vested CSRSUs at December 31, 2019		296,233		$	58.83
Granted		134,259		$	60.30
Vested		(154,653	)	$	49.44
Cancelled		(34,358	)	$	63.03
Non-vested CSRSUs at December 31, 2020		241,481		$	65.06	$	17,949,283
CSRSUs expected to vest in the future		213,305		$	65.17	$	15,854,961

The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $74.33 per share as of December 31, 2020. The fair value of CSRSUs vested and settled in cash for the years ended December 31, 2020, 2019, and 2018 was $9.3 million, $7.2 million and $7.7 million, respectively.

In the first six months of 2018, the Company granted awards of unregistered shares to its non-employee directors on a quarterly basis under its annual equity election plan. The awards were issued from the Company’s treasury stock and had no impact on the shares available for grant under the 2018 Omnibus Plan or the Prior Plan.

A summary of the Company’s non-employee director awards of unregistered shares granted by fiscal year is presented below.

Beginning on July 2, 2018, the Company granted awards of registered shares to its non-employee directors on an annual basis under the Omnibus Plan. A summary of the non-employee director awards is presented below:

	Number of Shares			Weighted- Average Grant Date Fair Value		Aggregate Intrinsic Value
Non-vested RSUs at July 1, 2018		—		$	—
Granted		11,606		$	72.35
Vested		(5,395	)	$	72.35
Cancelled		(1,243	)	$	72.35
Non-vested RSUs at December 31, 2018		4,968		$	72.35
Granted		9,732		$	73.94
Vested		(9,840	)	$	73.14
Cancelled		—		$	—
Non-vested RSUs at December 31, 2019		4,860		$	73.94
Granted		12,541		$	64.58
Vested		(10,891	)	$	68.82
Cancelled		—		$	—
Non-vested RSUs at December 31, 2020		6,510		$	64.47	$	483,888
RSUs expected to vest in the future		6,510		$	64.47	$	483,888

The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $74.33 per share as of December 31, 2020.

In 2015, the Company’s Board of Directors approved a performance-based share program (the “Program”) that provides for the issuance of PSAs to its senior management. Under the Program, the number of PSAs that the participant will receive depends on the Company’s achievement of two performance goals during two performance periods. The performance goals under the Program are based on (i) the Company’s compounded annual growth rate in EPS during a two-year performance period and (ii) the Company’s cumulative total shareholder return (“rTSR”) relative to its peer group during a performance period from the first day of the performance period (typically January 1 of the year awarded) to the last day of the third year of the performance period (typically December 31). The PSAs will only be eligible to vest following the expiration of the three-year performance period. Actual shares vested will be subject to both continued employment by the Company (barring certain exceptions allowing for partial performance periods) and actual financial measures achieved. The actual number of shares of common stock that will be issued to each participant at the end of the applicable performance period will be determined by multiplying the award by the product of two percentages, one based on the Company’s EPS performance and a second one based on the Company’s rTSR performance, subject to a minimum and maximum performance level. As of December 31, 2020, shares granted during 2018, 2019, and 2020 are within year three, two, and one of the performance period, respectively, and therefore have not fully vested. A total of 88,038 shares granted in 2017 vested during 2020 after meeting the performance goals, and a total of 94,178 shares (adjusted for partial performance periods) granted in 2018, 2019, and 2020 is expected to vest in the future.

	Number of Shares			Weighted- Average Grant Date Fair Value		Aggregate Intrinsic Value
Non-vested PSAs at January 1, 2018		187,022		$	39.95
Granted		45,136		$	65.05
Vested		(30,576	)	$	44.21
Cancelled		(32,096	)	$	43.72
Non-vested PSAs at December 31, 2018		169,486		$	45.15
Granted		85,928		$	62.07
Vested		(107,000	)	$	37.21
Cancelled		—		$	—
Non-vested PSAs at December 31, 2019		148,414		$	60.67
Granted		87,314		$	51.44
Vested		(88,038	)	$	38.81
Cancelled		(5,569	)	$	69.66
Non-vested PSAs at December 31, 2020		142,121		$	68.19	$	10,563,854
PSAs expected to vest in the future		94,178		$	69.76	$	7,000,251

The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $74.33 per share as of December 31, 2020. The fair value of the awards is estimated on the grant date using a Monte Carlo simulation model due to the market condition for the rTSR component. The fair value assumptions using the Monte Carlo simulation model for awards granted in 2020, 2019, and 2018 were:

	2020			2019			2018
Dividend Yield		1.0	%		0.7	%		0.9	%
Historical Volatility		35.7	%		29.3	%		31.9	%
Risk-Free Rate of Returns		0.4	%		2.4	%		2.4	%