Business Segments (Narrative) (Details)	9 Months Ended				12 Months Ended
	Sep. 30, 2011 International Energy Interest In National Methanol [Member]	Sep. 30, 2011 Duke Energy Interest In DukeNet [Member]	Sep. 30, 2011 Exxon Mobil Interest In DETM [Member]	Sep. 30, 2011 Duke Energy Interest In DETM [Member]	Dec. 31, 2010 Alinda Capital Partners Interest In DukeNet [Member]
Ownership interest	25.00%	50.00%	40.00%	60.00%	50.00%