FAIR VALUE MEASUREMENTS (Recurring Fair Value Measurements) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Liabilities, Fair Value Disclosure [Abstract]
Transfers Into Level 3	$ 0	$ 0
Transfers out of Level 3	0	0
Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	199,449	220,534
Time deposits and restricted cash	30,419	156
Employee loans	6,338	6,515
Total assets measured at fair value on recurring basis	236,206	227,205
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	0	37,400
Performance-based equity awards	5,364	3,223
Total liabilities measured at fair value on a recurring basis	5,364	40,623
Fair Value, Measurements, Recurring | Level 1
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	199,449	220,534
Time deposits and restricted cash	0	0
Employee loans	0	0
Total assets measured at fair value on recurring basis	199,449	220,534
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	0	0
Performance-based equity awards	0	0
Total liabilities measured at fair value on a recurring basis	0	0
Fair Value, Measurements, Recurring | Level 2
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0	0
Time deposits and restricted cash	30,419	156
Employee loans	0	0
Total assets measured at fair value on recurring basis	30,419	156
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	0	0
Performance-based equity awards	0	0
Total liabilities measured at fair value on a recurring basis	0	0
Fair Value, Measurements, Recurring | Level 3
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0	0
Time deposits and restricted cash	0	0
Employee loans	6,338	6,515
Total assets measured at fair value on recurring basis	6,338	6,515
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	0	37,400
Performance-based equity awards	5,364	3,223
Total liabilities measured at fair value on a recurring basis	$ 5,364	$ 40,623