Derivative Instruments and Hedging Activities - Effect of Derivative on Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized gain (loss) on derivative instruments	$ 56,686	$ 219,319	$ 0
Gain (loss) in derivative instruments not designated as hedges	56,686	145,891	0
Gain (loss) on derivative, net	56,686	75,116	57,002
Derivatives designated as hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gain (loss) on derivative instruments	0	(70,775)	57,002
Derivatives Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized gain (loss) on derivative instruments	(137,603)	137,603	0
Natural gas | Derivatives designated as hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gain (loss) on derivative instruments	0	(70,557)	52,733
Natural gas | Derivatives Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gain (loss) on derivative instruments	0	(73,020)	0
Crude oil and condensate | Derivatives designated as hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gain (loss) on derivative instruments	0	(218)	4,269
Crude oil and condensate | Derivatives Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gain (loss) on derivative instruments	0	(408)	0
Gain (loss) on derivative instruments | Derivatives Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gain (loss) on derivative instruments	$ 194,289	$ 81,716	$ 0