Derivative Financial Instruments (Details) (USD $)		12 Months Ended
	Dec. 31, 2013 Commodity contracts Derivative instruments not designated as hedging instruments gal MMBTU bbl	Dec. 31, 2013 Embedded Derivatives in commodity contracts Embedded derivative in natural gas processing and purchase contract	Dec. 31, 2013 Embedded Derivatives in commodity contracts Embedded derivative in electricity purchase contract	Dec. 31, 2012 Embedded Derivatives in commodity contracts Embedded derivative in electricity purchase contract
Derivative financial instruments
Notional quantity of crude oil contract (in bbl)	1,323,905
Notional quantity of natural gas contract (in MMBtu)	3,187,606
Natural Gas Liquids (gal)	125,470,405
Notional amount for embedded derivative in commodity contract (in Dth per day)		9,000
Producer's option to extend successive years, number		5 years
Estimated fair value of embedded derivative contract liability including portion allocable to host processing agreement		$ 91,815,000
Inception value for period from April 1, 2015 to December 31, 2022		(53,507,000)
Recorded value of embedded derivative contract liability		38,308,000
Estimated fair value of embedded derivative contract asset			$ 3,300,000	$ 6,100,000