MARKETABLE SECURITIES - SCHEDULE OF PROCEEDS FROM MATURITIES AND SALES OF CURRENT AVAILABLE-FOR-SALE-MARKETABLE SECURITIES (Details 2) - USD ($) |
3 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Oct. 28, 2015 |
Jun. 30, 2015 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Marketable Securities [Abstract] | |||||
| Proceeds from maturities and sales of available-for-sale marketable securities | $ 279,485,000 | $ 218,976,000 | $ 25,223,000 | ||
| Gross realized gains | 3,556,000 | 443,000 | 3,362,000 | ||
| Gross realized losses | $ 300,000 | $ 0 | $ 0 | $ 0 | |
| PlentyOfFish | |||||
| Business Acquisition | |||||
| Purchase price | $ 574,100,000 | ||||
| Match Group | PlentyOfFish | |||||
| Business Acquisition | |||||
| Purchase price | $ 575,000,000 | ||||