Outstanding Natural Gas Contracts That Are Not Designated for Hedge Accounting (Details) (Natural gas contracts [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	$ (11)
Collars [Member] | January 2014 - March 2014 [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(1)
Natural Gas Volumes	5,850,000
Derivative, Weighted Average Floor Price	3.75
Derivative, Weighted Average Ceiling Price	4.62
Collars [Member] | April 2014 - June 2014 [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	0
Natural Gas Volumes	5,915,000
Derivative, Weighted Average Floor Price	3.75
Derivative, Weighted Average Ceiling Price	4.62
Collars [Member] | July 2014 - September 2014 [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	0
Natural Gas Volumes	5,980,000
Derivative, Weighted Average Floor Price	3.75
Derivative, Weighted Average Ceiling Price	4.62
Collars [Member] | October 2014 - December 2014 [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(1)
Natural Gas Volumes	5,980,000
Derivative, Weighted Average Floor Price	3.75
Derivative, Weighted Average Ceiling Price	4.62
Collars [Member] | January 2015 - December 2015 [Member]
Derivative [Line Items]
Natural Gas Volumes	38,325,000
Derivative, Weighted Average Floor Price	3.93
Derivative, Weighted Average Ceiling Price	4.74
Derivative Asset, Fair Value, Total	2
Fixed-price swaps | January 2014 - March 2014 [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(6)
Natural Gas Volumes	21,150,000
Derivative, Swap Type, Average Fixed Price	3.98
Fixed-price swaps | April 2014 - June 2014 [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(3)
Natural Gas Volumes	21,385,000
Derivative, Swap Type, Average Fixed Price	3.98
Fixed-price swaps | July 2014 - September 2014 [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(4)
Natural Gas Volumes	21,620,000
Derivative, Swap Type, Average Fixed Price	3.98
Fixed-price swaps | October 2014 - December 2014 [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(5)
Natural Gas Volumes	21,620,000
Derivative, Swap Type, Average Fixed Price	3.98
Fixed-price swaps | January 2015 - December 2015 [Member]
Derivative [Line Items]
Natural Gas Volumes	49,275,000
Derivative, Swap Type, Average Fixed Price	4.28
Derivative Asset, Fair Value, Total	$ 7