DISCONTINUED OPERATIONS AND OTHER BUSINESS DISPOSITIONS (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Fair value of minority investments retained or acquired					$ 0	$ 2,022
Total net consideration received						1,300
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues		$ 592,883	$ 634,466		1,836,819	1,970,711
Total cost of revenue		286,894	325,041		882,287	1,023,768
Marketing expense		(92,717)	(101,456)		(286,051)	(288,456)
Selling, general and administrative expense		(160,214)	(214,828)		(676,399)	(677,109)
Restructuring		(35)	(11,503)		81	(18,818)
Other income, net		(4,860)	7,546		(39,832)	8,822
Income (loss) from discontinued operations, net of tax		0	(862)		0	(1,751)
Service
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues		289,214	302,458		886,663	919,884
Total cost of revenue		29,792	41,858		91,167	123,209
Product
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues		303,669	332,008		950,156	1,050,827
Total cost of revenue		$ 257,102	283,183		$ 791,120	900,559
Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Controlling stake percentage in subsidiary sold during period				83.00%
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Fair value of minority investments retained or acquired				$ 2,021
Cash proceeds received				3,462
Cash proceeds receivable				2,000
Less: transaction costs				1,394
Total net consideration received				6,089
Cumulative translation gain reclassified to earnings				14,718
Less: Net book value upon closing of the transactions				14,958
Less: Indemnification liabilities	[1]			5,365
Less: Unfavorable contract liability for transition services				2,114
Loss on dispositions			(362)	$ (1,630)		(1,630)
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Marketing expense			0			(1,239)
Selling, general and administrative expense			(500)			(11,784)
Restructuring			0			(778)
Other income, net			0			3,852
Income (loss) from discontinued operations before loss on dispositions and provision for income taxes			(500)			(40)
Provision for income taxes			0			(81)
Discontinued Operations, Disposed of by Sale | Service
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues			0			12,602
Total cost of revenue			0			2,557
Discontinued Operations, Disposed of by Sale | Product
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues			0			2,962
Total cost of revenue			$ 0			$ 3,098

[1] (1)See Note 9, Commitments and Contingencies, for additional information about the indemnification liabilities.