SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Restricted Cash and Restricted Cash Equivalents) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Changes in operating assets and liabilities:
Prepaid expenses and other assets	$ (1,765)	$ 2,036
Net cash provided by operating activities	169,088	121,580
Cash flows from investing activities:
Decrease in restricted cash and time deposits, net	418	(408)
Acquisition of businesses, net of cash acquired	(50,264)	(6,810)
Net cash used in investing activities	(77,833)	(24,124)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(8,660)	10,435
Net increase in cash, cash equivalents and restricted cash	103,446	148,107
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	685,108
Cash, cash equivalents and restricted cash, end of period	$ 686,301	512,771
As Originally Reported
Changes in operating assets and liabilities:
Prepaid expenses and other assets		4,436
Net cash provided by operating activities		123,980
Cash flows from investing activities:
Decrease in restricted cash and time deposits, net		(268)
Acquisition of businesses, net of cash acquired		(6,840)
Net cash used in investing activities		(24,014)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		10,286
Net increase in cash, cash equivalents and restricted cash		150,468
Cash, cash equivalents and restricted cash, beginning of period		362,025
Cash, cash equivalents and restricted cash, end of period		512,493
ASU 2016-18 \| Effect
Changes in operating assets and liabilities:
Prepaid expenses and other assets		(2,400)
Net cash provided by operating activities		(2,400)
Cash flows from investing activities:
Decrease in restricted cash and time deposits, net		(140)
Acquisition of businesses, net of cash acquired		30
Net cash used in investing activities		(110)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		149
Net increase in cash, cash equivalents and restricted cash		(2,361)
Cash, cash equivalents and restricted cash, beginning of period		2,639
Cash, cash equivalents and restricted cash, end of period		$ 278

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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