FAIR VALUE OF CERTAIN FINANCIAL ASSETS AND LIABILITIES (Details 2) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Fair value amounts included in the carrying value of
Cash and cash equivalents	$ 418,197	$ 354,842	$ 409,911	$ 328,349
Short-term investments	281,218	244,649
Investments	30,202	44,189
Level 1
Fair value amounts included in the carrying value of
Cash and cash equivalents	378,153	311,202
Short-term investments	60,589	66,522
Total	439,012	377,724
Level 2
Fair value amounts included in the carrying value of
Cash and cash equivalents	40,044	43,640
Short-term investments	194,925	154,064
Total	234,969	197,704
Level 3
Fair value amounts included in the carrying value of
Short-term investments	25,434	24,063
Investments	30,202	44,189
Prepaid expenses and other current assets	1,632	2,983
Other assets	2,459	785
Total	59,727	72,020
Total fair value
Fair value amounts included in the carrying value of
Cash and cash equivalents	418,197	354,842
Short-term investments	281,218	244,649
Investments	30,202	44,189
Prepaid expenses and other current assets	1,632	2,983
Other assets	2,459	785
Total	$ 733,708	$ 647,448