Accounting for Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Stock-based Compensation Expense

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

Outstanding Stock Option Activity

The following table summarizes the changes in outstanding stock options:

	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

Schedule of Stock Options Outstanding by Exercise Price Range

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

Summary of Non-employee Director Awards

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

For the Year ended December 31,	Number of shares Granted		Weighted- Average Grant Date Fair Value
2018		7,985	$	60.36

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

Summary of Performance Shares Activity

A summary of the Company’s PSAs is presented below.

	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

Schedule of Fair Value Assumptions using Monte Carlo Simulation Model for Awards Granted

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	%

Restricted Stock Units (RSUs)

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Restricted Stock Unit Activity

A summary of the Company’s RSUs is presented below. 

	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

Cash Settled RSUs

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Restricted Stock Unit Activity

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