FAIR VALUE OF CERTAIN FINANCIAL ASSETS AND LIABILITIES (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair value amounts included in the carrying value of
Cash and cash equivalents	$ 222,514	$ 359,331	$ 354,842	$ 328,349
Short-term investments	97,042	411,282
Investments	21,393	23,194
Level 1
Fair value amounts included in the carrying value of
Cash and cash equivalents	211,087	311,908
Short-term investments		8,034
Total	211,087	319,942
Level 2
Fair value amounts included in the carrying value of
Cash and cash equivalents	11,427	47,423
Short-term investments	95,279	390,590
Total	106,706	438,013
Level 3
Fair value amounts included in the carrying value of
Short-term investments	1,763	12,658
Investments	21,393	23,194
Prepaid expenses and other current assets	225	873
Other assets	1,704	2,168
Total	25,085	38,893
Total fair value
Fair value amounts included in the carrying value of
Cash and cash equivalents	222,514	359,331
Short-term investments	97,042	411,282
Investments	21,393	23,194
Prepaid expenses and other current assets	225	873
Other assets	1,704	2,168
Total	$ 342,878	$ 796,848