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SIGNIFICANT ACCOUNTING POLICIES Additional Information (Details) (USD $)
Mar. 31, 2012
Dec. 31, 2011
Significant Accounting Policies [Line Items]    
Net unrealized holding gains on available for-sale securities $ 22,484,000 $ (516,000)
Trade Accounts Receivable
   
Significant Accounting Policies [Line Items]    
Allowance for doubtful accounts 15,900,000 15,800,000
Noncurrent Assets Member
   
Significant Accounting Policies [Line Items]    
Available-for-sale securities, fair value of DIO bond 82,300,000 47,800,000
Net unrealized holding gains on available for-sale securities $ 32,000,000 $ 11,500,000