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Other Current Assets and Liabilities	6 Months Ended
Other Current Assets and Liabilities	Jun. 30, 2013
Other Current Assets and Liabilities [Abstract]
Other Current Assets and Liabilities [Text Block]	Other Current Assets and Liabilities Included in other current assets on the Condensed Consolidated Balance Sheets at December 31, 2012 and June 30, 2013 were $12 million and $9 million, respectively, of margin deposits and $86 million and $23 million, respectively, of under-recovered gas cost. Included in other current liabilities on the Condensed Consolidated Balance Sheets at December 31, 2012 and June 30, 2013 were $6 million and $53 million, respectively, of over-recovered gas cost.