Annual report pursuant to Section 13 and 15(d)

Investments (Details)

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Investments (Details) (USD $)
In Thousands, unless otherwise specified
1 Months Ended 12 Months Ended
Jan. 31, 2010
Dec. 31, 2011
Dec. 31, 2010
Investments (Textual) [Abstract]      
Sale of auction rate of securities $ 9,456    
Gain on sale of auction rate securities     425
Long-term restricted investments   3,973 3,396
Obligations under letters of credit liquidated   250  
New letter of credit agreement   $ 826