Fair Value of Financial Investments and Liabilities (Details Textuals) (USD $) In Billions	Sep. 30, 2011	Dec. 31, 2010
Fair Value of Financial Investments and Liabilities (Textuals) [Abstract]
Estimated market value of long-term and short-term debt	$ 3.9	$ 4.2
Aggregate carrying value of long-term and short-term debt	$ 4.0	$ 4.1