ACQUIRED INTANGIBLE ASSETS, NET (Summary of Acquired Intangible Assets) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Deletions	$ 26,700
Finite-lived Intangible Assets Acquired	80,979	$ 116,893
Finite-Lived Intangible Assets, Accumulated Amortization	27,544	52,869
Finite-Lived Intangible Assets, Translation Adjustments	5,433	5,652
Impairment of intangible assets		(9,252)
Acquired intangible assets, net	48,002	49,120
Technology Equipment [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	5,228	10,308
Finite-Lived Intangible Assets, Accumulated Amortization	4,597	9,677
Finite-Lived Intangible Assets, Translation Adjustments	631	631
Impairment of intangible assets		0
Acquired intangible assets, net	0	0
Trademarks, Other [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	13,394	23,194
Finite-Lived Intangible Assets, Accumulated Amortization	8,236	14,379
Finite-Lived Intangible Assets, Translation Adjustments	2,187	2,286
Impairment of intangible assets		(3,168)
Acquired intangible assets, net	2,971	3,361
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	14,500	28,473
Finite-Lived Intangible Assets, Accumulated Amortization	6,357	13,518
Finite-Lived Intangible Assets, Translation Adjustments	2,112	2,112
Impairment of intangible assets		(6,084)
Acquired intangible assets, net	6,031	6,759
Candidate Database [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	8,857	15,918
Finite-Lived Intangible Assets, Accumulated Amortization	8,354	15,295
Finite-Lived Intangible Assets, Translation Adjustments	503	623
Impairment of intangible assets		0
Acquired intangible assets, net	0	0
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	39,000	39,000
Finite-Lived Intangible Assets, Accumulated Amortization	0	0
Finite-Lived Intangible Assets, Translation Adjustments	0	0
Impairment of intangible assets		0
Acquired intangible assets, net	$ 39,000	$ 39,000