INVESTMENTS - Additional Information (Details) - USD ($) $ in Thousands			1 Months Ended		3 Months Ended									12 Months Ended
	May 09, 2016	May 27, 2015	Sep. 30, 2018	Feb. 14, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 21, 2017	Feb. 01, 2017	Jan. 03, 2017
Schedule of Equity Method Investments [Line Items]
Equity Securities without Readily Determinable Fair Value, Amount					$ 75,171				$ 24,273					$ 75,171	$ 24,273	$ 25,438
Equity Investment, Transfer to Other Equity Investments															4,008
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount															(4,574)
Foreign Currency Translation, Equity Investment														141	(599)
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount														51,397
Equity Investment, Dispositions														(640)
Revenues					612,316	$ 495,612	$ 532,577	$ 578,410	799,927	$ 592,883	$ 617,396	$ 626,540
Disposition of Intangible Assets, Gross Consideration Received	$ 16,000
Assets, Current					887,913				998,629					887,913	998,629
Proceeds from Sale of Debt Securities, Available-for-sale			$ 8,600
Impairments of investments														9,961	10,156	2,944
Investments (including $1,405 and $84,242 at December 31, 2019 and December 31, 2018 at fair value)					76,576				108,515					76,576	108,515
Equity method investments					1,405				73,902					1,405	73,902	82,966	$ 82,584	$ 400
(Gain) loss from changes in fair value of investments														(72,497)	(9,064)	382
Gain (Loss) on Disposition of Business	$ 7,600
Gross Profit					310,041	$ 277,940	292,132	306,016	366,069	$ 305,989	$ 323,658	$ 324,885		1,186,129	1,320,601	1,333,861
Other Income (Expense)
Schedule of Equity Method Investments [Line Items]
Impairments of investments														10,000	5,600	2,900
Monster LP
Schedule of Equity Method Investments [Line Items]
Assets, Current					73,598				85,844					73,598	85,844
Equity Method Investment, Summarized Financial Information, Net Income (Loss)														(105,212)	(132,276)	(124,873)
Assets, Noncurrent					436,809				482,505					436,809	482,505
Equity method investments					0				69,400					0	69,400
(Gain) loss from changes in fair value of investments							$ 27,900	$ 41,500						(69,408)	$ (9,509)	249
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate								26.00%							21.00%
Fair-Value Option Investments, Recapitalization Transaction, Ownership Percentage Outstanding																			9.00%
Nearbuy
Schedule of Equity Method Investments [Line Items]
Revenues														5,507	$ 6,016	3,839
Assets, Current					3,611				5,286					3,611	5,286
Equity Method Investment, Summarized Financial Information, Net Income (Loss)														(1,777)	(13,594)	15,122
Assets, Noncurrent					40,083				46,940					40,083	46,940
Equity method investments					1,400				4,500					1,400	4,500
(Gain) loss from changes in fair value of investments					3,100									(3,089)	445	133
Proceeds from Contributed Capital													$ 3,000				$ 17,000
Preferred Stock, Liquidation Preference, Value																				$ 20,000
Gross Profit														4,944	5,857	3,405
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest														(1,777)	(13,594)	$ 15,122
Other Equity Investments
Schedule of Equity Method Investments [Line Items]
Equity method investments					75,171				24,273					75,171	24,273
Fair Value Option Investments
Schedule of Equity Method Investments [Line Items]
Equity method investments					$ 1,405				$ 73,902					$ 1,405	$ 73,902
Capital Unit, Class A-1 [Member] | All Holders [Member]
Schedule of Equity Method Investments [Line Items]
Fair-Value Option Investments, Recapitalization Transaction, Liquidation Preference				$ 150,000
Capital Unit, Class A-1 [Member] | Monster LP
Schedule of Equity Method Investments [Line Items]
Fair-Value Option Investments, Recapitalization Transaction, Liquidation Preference				$ 85,000
Monster LP | Capital Unit, Class A [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Interest in Partnership Unit		$ 285,000
Monster LP | Capital Unit, Class A-1 [Member]
Schedule of Equity Method Investments [Line Items]
Fair-Value Option Investment, Recapitalization Transaction, Shares Issued				16,609,195
Minimum
Schedule of Equity Method Investments [Line Items]
Available for Sale Securities, Redeemable Preferred Shares, Ownership Percentage					19.00%				19.00%					19.00%	19.00%
Minimum | Capital Unit, Class A-1 [Member] | Monster LP
Schedule of Equity Method Investments [Line Items]
Stock or Units Available for Distributions				950,000,000.0
Maximum
Schedule of Equity Method Investments [Line Items]
Available for Sale Securities, Redeemable Preferred Shares, Ownership Percentage					25.00%				25.00%					25.00%	25.00%
Maximum | Capital Unit, Class A-1 [Member] | Monster LP
Schedule of Equity Method Investments [Line Items]
Stock or Units Available for Distributions				1,494,000,000.0