Derivative Commodity Instruments - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) counterparty	Sep. 30, 2015 USD ($)
Derivative [Line Items]
Gain on fair value of derivatives	$ 20,412	$ 107,173	$ (40,005)	$ 90,245
Commodity contracts
Derivative [Line Items]
Number of counterparties, net loss position | counterparty			11
Number of counterparties, net gain position | counterparty			4
Commodity contracts | Morgan Stanley Capital Group Inc
Derivative [Line Items]
Gain on fair value of derivatives			$ 2,000
Commodity contracts | BP Corporation North America, Inc.
Derivative [Line Items]
Gain on fair value of derivatives			$ 1,000