Basis of Presentation Basis of Presentation Revenues (Details) (Oil and Gas Revenue [Member], Customer Concentration Risk [Member])	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Shell Trading Co [Member]
Concentration Risk [Line Items]
Net oil and gas revenues (percent)	30.00%	18.00%	19.00%
Laclede Energy [Member]
Concentration Risk [Line Items]
Net oil and gas revenues (percent)	17.00%	20.00%	17.00%
JP Morgan Ventures Energy [Member]
Concentration Risk [Line Items]
Net oil and gas revenues (percent)	12.00%
Texon LP [Member]
Concentration Risk [Line Items]
Net oil and gas revenues (percent)		15.00%	17.00%
Gary Williams [Member]
Concentration Risk [Line Items]
Net oil and gas revenues (percent)		11.00%	10.00%