STOCK-BASED COMPENSATION Performance-based Awards and Restricted Stock Units (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
Jun. 30, 2020 USD ($) $ / shares shares
Restricted Stock Units (RSUs)
Shares
Outstanding at January 1, 2020	860
Granted	191
Vested	(288)
Forfeited	(11)
Outstanding at June 30, 2020	752
Outstanding and expected to vest at June 30, 2020	690
Weighted- Average Grant Date Fair Value Per Share (in dollars per share)
Outstanding at January 1, 2020 \| $ / shares	$ 62.66
Granted \| $ / shares	85.96
Vested \| $ / shares	60.09
Forfeited \| $ / shares	66.16
Outstanding at June 30, 2020 \| $ / shares	$ 69.51
Weighted-Average Remaining Contractual Term (In years)
Outstanding at June 30, 2020	1 year 10 months 20 days
Outstanding and expected to vest at June 30, 2020	1 year 9 months 25 days
Aggregate Intrinsic Value (In thousands)
Outstanding at June 30, 2020 \| $	$ 88,770
Outstanding and expected to vest at June 30, 2020 \| $	$ 81,463
Long-Term Performance-Based Awards (PRSUs)
Shares
Outstanding at January 1, 2020	144
Granted	73
Vested	0
Forfeited	0
Outstanding at June 30, 2020	217
Outstanding and expected to vest at June 30, 2020	100
Weighted- Average Grant Date Fair Value Per Share (in dollars per share)
Outstanding at January 1, 2020 \| $ / shares	$ 64.05
Granted \| $ / shares	98.75
Vested \| $ / shares	0
Forfeited \| $ / shares	0
Outstanding at June 30, 2020 \| $ / shares	$ 75.70
Weighted-Average Remaining Contractual Term (In years)
Outstanding at June 30, 2020	1 year 6 months
Outstanding and expected to vest at June 30, 2020	2 years 2 months 23 days
Aggregate Intrinsic Value (In thousands)
Outstanding at June 30, 2020 \| $	$ 25,540
Outstanding and expected to vest at June 30, 2020 \| $	$ 11,808
Performance Based Awards (PSUs)
Shares
Outstanding at January 1, 2020	61
Granted	73
Vested	(61)
Forfeited	0
Outstanding at June 30, 2020	73
Outstanding and expected to vest at June 30, 2020	50
Weighted- Average Grant Date Fair Value Per Share (in dollars per share)
Outstanding at January 1, 2020 \| $ / shares	$ 70.11
Granted \| $ / shares	92.12
Vested \| $ / shares	70.11
Forfeited \| $ / shares	0
Outstanding at June 30, 2020 \| $ / shares	$ 92.12
Weighted-Average Remaining Contractual Term (In years)
Outstanding at June 30, 2020	6 months
Outstanding and expected to vest at June 30, 2020	6 months
Aggregate Intrinsic Value (In thousands)
Outstanding at June 30, 2020 \| $	$ 8,652
Outstanding and expected to vest at June 30, 2020 \| $	$ 5,961
Minimum [Member] \| Long-Term Performance-Based Awards (PRSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Performance Based Awards Shares Released As Percentage Of Target Number	0.00%
Minimum [Member] \| Performance Based Awards (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Performance Based Awards Shares Released As Percentage Of Target Number	0.00%
Maximum [Member] \| Long-Term Performance-Based Awards (PRSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Performance Based Awards Shares Released As Percentage Of Target Number	200.00%
Maximum [Member] \| Performance Based Awards (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Performance Based Awards Shares Released As Percentage Of Target Number	200.00%

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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