Consolidated statements of comprehensive income (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Comprehensive income
Net income	$ 209,293us-gaap_NetIncomeLoss	$ 55,687us-gaap_NetIncomeLoss	$ 64,403us-gaap_NetIncomeLoss
Other comprehensive (loss) income
Reclassification adjustment for hedge gains included in gain from oil hedging activities in the consolidated statements of operations	0	(37,134)	(46,746)
Income tax benefit related to other comprehensive loss	0	13,911	18,123
Other comprehensive loss, net of tax	0	(23,223)	(28,623)
Comprehensive income	$ 209,293us-gaap_ComprehensiveIncomeNetOfTax	$ 32,464us-gaap_ComprehensiveIncomeNetOfTax	$ 35,780us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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