SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Restricted Cash and Restricted Cash Equivalents) (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Changes in operating assets and liabilities:
Prepaid expenses and other assets	$ (4,495)	$ 973
Net cash provided by operating activities	66,789	59,333
Cash flows from investing activities:
Decrease in restricted cash and time deposits, net	418	13
Acquisition of businesses, net of cash acquired	(50,264)	(6,810)
Net cash used in investing activities	(68,314)	(17,625)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(7,645)	5,912
Net increase in cash, cash equivalents and restricted cash	2,421	81,752
Cash, cash equivalents and restricted cash, beginning of period	582,585
Cash, cash equivalents and restricted cash, beginning of period	582,855	364,664
Cash, cash equivalents and restricted cash, end of period	584,081
Cash, cash equivalents and restricted cash, end of period	$ 585,276	446,416
As Reported
Changes in operating assets and liabilities:
Prepaid expenses and other assets		736
Net cash provided by operating activities		59,096
Cash flows from investing activities:
Decrease in restricted cash and time deposits, net		94
Acquisition of businesses, net of cash acquired		(6,840)
Net cash used in investing activities		(17,574)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		5,822
Net increase in cash, cash equivalents and restricted cash		81,476
Cash, cash equivalents and restricted cash, beginning of period		362,025
Cash, cash equivalents and restricted cash, end of period		443,501
ASU 2016-18 \| Effect
Changes in operating assets and liabilities:
Prepaid expenses and other assets		237
Net cash provided by operating activities		237
Cash flows from investing activities:
Decrease in restricted cash and time deposits, net		(81)
Acquisition of businesses, net of cash acquired		(30)
Net cash used in investing activities		(51)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		90
Net increase in cash, cash equivalents and restricted cash		276
Cash, cash equivalents and restricted cash, beginning of period		2,639
Cash, cash equivalents and restricted cash, end of period		$ 2,915

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes.

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Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

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