Accounting for Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018, 2017, and 2016, the unrecognized compensation expense at December 31, 2018, and the weighted-average period to recognize the remaining unrecognized shares are as follows:

	Stock-Based Compensation Expense
	Recognized as of December 31,						Unrecognized
	2018		2017		2016		December 31, 2018		Weighted-Average Period to Recognize (years)
Stock Options	$	—	$	164	$	909	$	—		—
Restricted Stock Units		7,410		7,080		6,325		13,484		1.8
Cash-Settled Restricted Stock Units		8,214		7,253		7,091		10,550		1.6
Non-Employee Director Awards		764		671		741		327		0.4
Performance Shares		3,193		2,376		877		3,000		1.5
Total	$	19,581	$	17,544	$	15,943	$	27,361

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, 2016		723,005		$	28.62
Exercised		(128,301	)	$	23.65
Granted	—			$	—
Forfeited/Expired		(7,297	)	$	40.68
Outstanding at December 31, 2016		587,407		$	29.56
Exercised		(175,909	)	$	26.84
Granted		—		$	—
Forfeited/Expired		—		$	—
Outstanding at December 31, 2017		411,498		$	30.71
Exercised		(209,688	)	$	27.86
Granted		—		$	—
Forfeited/Expired		—		$	—
Outstanding at December 31, 2018		201,810		$	33.68	$	6,276,432
Vested plus expected to vest at December 31, 2018		201,810		$	33.68	$	6,276,432
Exercisable at December 31, 2018		201,810		$	33.68	$	6,276,432

Schedule of Stock Options Outstanding by Exercise Price Range

Information regarding stock options outstanding as of December 31, 2018 is summarized below:

	OPTIONS OUTSTANDING						OPTIONS EXERCISABLE
Range of Exercise Prices	Number Outstanding As of December 31, 2018		Weighted Average Remaining Contractual Term		Weighted Average Exercise Price		Number Exercisable As of December 31, 2018		Weighted Average Exercise Price
$21.77 to $25.00		1,915		2.3	$	21.77		1,915	$	21.77
$25.01 to $28.00		100,114		4.1	$	26.93		100,114	$	26.93
$28.01 to $40.68		99,781		5.2	$	40.68		99,781	$	40.68
$21.77 to $41.00		201,810		4.7	$	33.68		201,810	$	33.68

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
2016		15,299	$	39.32
2017		13,861	$	48.41
2018		7,985	$	60.36

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 RSAs at January 1, 2018		—		$	—
Granted		11,606		$	72.35
Vested		(5,395	)	$	72.35
Cancelled		(1,243	)	$	72.35
Non-vested RSAs at December 31, 2018		4,968		$	72.35	$	321,827
RSAs expected to vest in the future		4,968		$	72.35	$	321,827

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, 2016		58,822		$	44.21
Granted		74,574		$	37.75
Vested		—		$	—
Cancelled		(3,422	)	$	41.61
Non-vested PSAs at December 31, 2016		129,974		$	40.57
Granted		60,929		$	38.81
Vested		—		$	—
Cancelled		(3,881	)	$	42.83
Non-vested PSAs at December 31, 2017		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	$	10,979,303
PSAs expected to vest in the future		97,309		$	50.35	$	6,303,674

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, 2016		555,904		$	35.40
Granted		240,868		$	34.68
Vested		(221,659	)	$	32.45
Cancelled		(67,115	)	$	37.60
Non-vested RSUs at December 31, 2016		507,998		$	36.12
Granted		194,227		$	41.41
Vested		(179,974	)	$	35.19
Cancelled		(58,664	)	$	36.04
Non-vested RSUs at December 31, 2017		463,587		$	38.71
Granted		235,480		$	65.37
Vested		(169,279	)	$	38.66
Cancelled		(54,742	)	$	47.50
Non-vested RSUs at December 31, 2018		475,046		$	50.93	$	30,773,480
RSUs expected to vest in the future		425,272		$	49.77	$	27,549,127

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, 2016		446,663		$	37.18
Granted		233,790		$	34.29
Vested		(146,619	)	$	34.70
Cancelled		(70,812	)	$	37.55
Non-vested CSRSUs at December 31, 2016		463,022		$	35.96
Granted		174,419		$	42.06
Vested		(161,576	)	$	40.78
Cancelled		(83,949	)	$	36.43
Non-vested CSRSUs at December 31, 2017		391,916		$	38.80
Granted		147,103		$	60.84
Vested		(147,759	)	$	38.71
Cancelled		(51,695	)	$	43.07
Non-vested CSRSUs at December 31, 2018		339,565		$	47.73	$	21,997,021
CSRSUs expected to vest in the future		301,532		$	47.00	$	19,533,238