Fair Value Measurements on a Recurring Basis (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Assets:
Commodity derivatives		$ 13,807	$ 60,843
Commodity derivatives	[1]	(589)	(17,149)
Commodity derivatives		13,218	43,694
Liabilities:
Commodity derivatives		2,830	17,149
Commodity derivatives	[1]	(589)	(17,149)
Commodity derivatives		$ 2,241	$ 0

[1] Represents counterparty netting under agreements governing such derivatives.