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FAIR VALUE OF CERTAIN FINANCIAL ASSETS AND LIABILITIES (Details 4) (USD $)
 3 Months Ended 12 Months Ended 12 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Dec. 31, 2011
Mar. 31, 2012
Auction rate securities
Dec. 31, 2011
2011 ARS Agreement
Jun. 30, 2011
2011 ARS Agreement
Dec. 31, 2011
2010 ARS Agreement
Mar. 31, 2010
2010 ARS Agreement
Mar. 31, 2012
Put options related to auction rate securities
Oct. 01, 2013
2011 Put Option
Jul. 01, 2013
2011 Put Option
Mar. 31, 2012
2010 Put Option
ARS Agreement                        
Face value of investments       $ 29,100,000                
Amortized Cost 441,452,000   434,476,000 21,900,000                
Fair value of available-for-sale securities       3,300,000                
Impairment of investments available-for-sale       5,000,000                
Trading auction rate securities, in short-term and long-term investments       18,600,000                
Impairment of investments, trading securities       2,200,000                
Amount of securities of par value           24,500,000   54,200,000   1,000,000 1,000,000  
Redemption of investment securities at par through normal market channels         3,700,000   38,500,000          
Fair market value of investments                 1,600,000      
Redemption of investment securities through the exercise of the put option                       15,700,000
Resulted gain or loss on revaluation of investment securities included in other income $ 400,000 $ 300,000