CAPITAL STOCK AND SHARE-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Employee Stock Purchase Plan Activity

The following is a detail of the purchases that were made under the plan:

Employee Stock Purchase Plan Period	Shares Issued	Price
2017 and Prior	3,089,489	$	15.25
January 1, 2018 to March 31, 2018	10,913	51.29
April 1, 2018 to June 30, 2018	8,673	72.64
July 1, 2018 to September 30, 2018	6,052	106.22
October 1, 2018 to December 31, 2018	7,856	99.54
January 1, 2019 to March 31, 2019	7,181	104.77
April 1, 2019 to June 30, 2019	8,230	103.20
July 1, 2019 to September 30, 2019	7,216	111.36
October 1, 2019 to December 31, 2019	6,063	141.88
	3,151,673

Schedule of Share-based Payment Award Valuation Assumptions

The fair values of the awards were estimated using the following assumptions for each 2019, 2018 and 2017:

	For the Years Ended December 31,
	2019	2018	2017
Risk Free Rate	1.44% - 2.53%	2.56% - 3.04%	1.99% - 2.16%
Expected Volatility	42.46% - 43.83%	42.00% - 45.32%	50.18% - 51.81%
Expected Term	6.00 - 6.25 years	4.12 - 6.25 years	5.78 - 6.25 years
Weighted Average Fair Value	$54.42	$42.48	$28.02
Dividend Yield	—%	—%	—%

Schedule of Stock Options Activity

The following table presents our non-vested stock option activity for 2019:

	Number of Shares		Weighted Average Grant Date Fair Value
Non-vested stock options at January 1, 2019	370,470		$	30.97
Granted	142,122		54.42
Vested	(194,638	)	31.19
Forfeited	(12,204	)	32.84
Non-vested stock options at December 31, 2019	305,750		$	41.66

The following table presents our stock option activity for 2019:

	Number of Shares		Weighted Average Exercise Price		Weighted Average Contractual Life (Years)
Outstanding options at January 1, 2019	833,315		$	36.79	6.76
Granted	142,122		121.32
Exercised	(87,068	)	41.48
Canceled, forfeited or expired	(12,395	)	66.18
Outstanding options at December 31, 2019	875,974		$	49.62	6.26
Exercisable options at December 31, 2019	570,224		$	29.73	5.31

Schedule of Non-Vested Stock Activity

The following table presents our non-vested stock activity for 2019:

	Number of Shares		Weighted Average Grant Date Fair Value
Non-vested stock at January 1, 2019	14,904		$	80.54
Granted	9,859		119.12
Vested	(14,904	)	80.54
Canceled, forfeited or expired	—		—
Non-vested stock at December 31, 2019	9,859		$	119.12

Schedule of Non-Vested Stock Unit Activity

The following table presents our service-based non-vested stock units activity for 2019:

	Number of  Shares		Weighted Average Grant Date Fair Value
Non-vested stock units at January 1, 2019	240,400		$	69.49
Granted	82,605		123.70
Vested	(78,119	)	58.75
Canceled, forfeited or expired	(13,468	)	79.68
Non-vested stock units at December 31, 2019	231,418		$	91.87

Schedule of Nonvested Performance-based Units Activity

The following table presents our performance-based non-vested stock units activity for 2019:

	Number of  Shares		Weighted Average Grant Date Fair Value
Non-vested stock units at January 1, 2019	226,677		$	65.76
Granted	102,585		128.89
Vested	(101,156	)	61.12
Canceled, forfeited or expired	(20,682	)	82.72
Non-vested stock units at December 31, 2019	207,424		$	97.55