Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements payable within one year (or the operating cycle, if longer).

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Amount of cash paid related to share-based compensation liabilities.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Percentage of vesting of share-based compensation awards.

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STOCK-BASED COMPENSATION (Retricted Stock and Restricted Stock Units) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Liability associated with stock-based awardsurrent	$ 9,920	$ 9,920	$ 5,964
Equity Classified Award \| Performance Targets \| Equity-Settled Award \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	2,779	$ 2,779
Unrecognized compensation cost, period for recognition		1 year 10 months 15 days
Award accelerated compensation cost	835
Equity Classified Award \| Service Period \| Equity-Settled Award \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	38	$ 38
Unrecognized compensation cost, period for recognition		1 year 6 months 7 days
Equity Classified Award \| Service Period \| Equity-Settled Award \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	51,655	$ 51,655
Unrecognized compensation cost, period for recognition		2 years 6 months 27 days
Liability Classified Award \| Service Period \| Cash-Settled Award \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	23,251	$ 23,251
Unrecognized compensation cost, period for recognition		2 years 3 months 12 days
Cash paid to settle awards		$ 10,349	3,811	$ 0
Liability Classified Award \| Service Period \| Cash-Settled Award \| Restricted Stock Units (RSUs) \| Deferred compensation due to employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Liability associated with stock-based awardsurrent	$ 9,920	$ 9,920	$ 5,964
Business acquisitions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)		3 years
Year One \| Business acquisitions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		33.30%
Year Two \| Business acquisitions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		33.30%
Year Three \| Business acquisitions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		33.30%