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Fair Value of Financial Instruments
12 Months Ended
Dec. 31, 2011
Fair Value of Financial Instruments [Abstract]  
Fair Value of Financial Instruments [Text Block]
Fair Value of Financial Instruments

Our estimates of the fair value of (i) accounts receivable, accounts payable and accrued expenses approximate carrying value due to the relatively short maturity of these instruments; and (ii) our publicly traded debt is based on observable market data, and our debt that is not traded publicly is based on estimated effective borrowing rates for debt with similar terms, loan to estimated fair value and remaining maturities. The estimated fair value of our debt was $1.7 billion at December 31, 2011 and 2010 (with a carrying value of $1.6 billion and $1.5 billion at December 31, 2011 and 2010, respectively).

Disclosures about fair value of financial instruments are based on pertinent information available to management as of December 31, 2011.  Considerable judgment is necessary to interpret market data and develop estimated fair value.  Accordingly, the estimates presented herein are not necessarily indicative of the amounts that we could realize on disposition of the financial instruments. The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts.