FAIR VALUE OF CERTAIN FINANCIAL ASSETS AND LIABILITIES (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair value amounts included in the carrying value of
Cash and cash equivalents	$ 211,349	$ 222,514	$ 359,331	$ 354,842
Short-term investments	402,247	97,042
Investments	9,792	21,393
Asset transfers between Level 1 and Level 2 measurements	0	0
Level 1
Fair value amounts included in the carrying value of
Cash and cash equivalents	199,402	211,087
Total	199,402	211,087
Level 2
Fair value amounts included in the carrying value of
Cash and cash equivalents	11,947	11,427
Short-term investments	395,855	95,279
Total	407,802	106,706
Level 3
Fair value amounts included in the carrying value of
Short-term investments	6,392	1,763
Investments	9,792	21,393
Prepaid expenses and other current assets	486	225
Other assets	606	1,704
Total	17,276	25,085
Total fair value
Fair value amounts included in the carrying value of
Cash and cash equivalents	211,349	222,514
Short-term investments	402,247	97,042
Investments	9,792	21,393
Prepaid expenses and other current assets	486	225
Other assets	606	1,704
Total	$ 624,480	$ 342,878