STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2018

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

Schedule of Changes in Outstanding Stock Options

Stock options outstanding at December 31, 2018 and changes during the year ended December 31, 2018 are as follows:

	December 31, 2018
	Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (In Years)	Aggregate Intrinsic Value
	(Shares and intrinsic value in thousands)
Options outstanding at January 1, 2018	6,586		$	60.57
Granted	80		152.53
Exercised	(774	)	52.56
Forfeited	(72	)	57.52
Expired	(6	)	19.51
Options outstanding at December 31, 2018	5,814		$	62.97	6.1	$	698,128
Options exercisable	3,592		$	59.64	5.3	$	443,293

Schedule of Information for Stock Options Outstanding and Exercisable

The following table summarizes the information about stock options outstanding and exercisable at December 31, 2018:

	Options Outstanding				Options Exercisable
Range of Exercise Prices	Outstanding at December 31, 2018	Weighted- Average Remaining Contractual Life in Years	Weighted- Average Exercise Price		Exercisable at December 31, 2018	Weighted- Average Remaining Contractual Life in Years	Weighted- Average Exercise Price
	(Shares in thousands)
$20.01 to $30.00	30	1.1	$	21.60	30	1.1	$	21.60
$30.01 to $40.00	389	2.3	32.30		389	2.3	32.30
$40.01 to $50.00	1,541	5.8	43.35		961	5.0	44.26
$50.01 to $60.00	246	3.2	59.85		244	3.2	59.86
$60.01 to $70.00	1,173	6.3	65.27		767	6.0	65.62
$70.01 to $80.00	1,840	7.4	75.33		822	6.8	74.72
$80.01 to $90.00	500	6.3	84.31		375	6.3	84.31
Greater than $90.01	95	9.1	148.30		4	8.9	125.08
	5,814	6.1	62.97		3,592	5.3	59.64

Schedule of Weighted Average Assumptions

The following are the weighted average assumptions used in the Black-Scholes option pricing model:

	Years Ended December 31,
	2018		2017		2016
Expected volatility	27	%	29	%	29	%
Risk-free interest rate	2.7	%	2.0	%	1.2	%
Expected term	6.2 years		5.2 years		4.8 years
Dividend yield	—	%	—	%	—	%

Schedule of Outstanding Unvested RSUs and PSUs

Unvested RSUs and PSUs outstanding at December 31, 2018 and changes during the year ended December 31, 2018 are as follows:

	RSUs				PSUs
	Number of shares		Weighted Average Grant Date Fair Value		Number of shares		Weighted Average Grant Date Fair Value
	(Shares in thousands)
Unvested at January 1, 2018	360		$	80.81	130		$	76.00
Granted	153		183.33		30		152.53
Vested	(49	)	78.54		—		—
Forfeited	(5	)	98.81		(17	)	76.00
Unvested at December 31, 2018	459		$	115.12	143		$	92.02