Derivatives (Details 2) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Amount of Gain or (Loss) Recognized in Earnings
Gain (loss) on commodity derivatives	$ (20,289)	$ 12,519	$ 4,789
Nondesignated \| Commodity Contract
Amount of Gain or (Loss) Recognized in Earnings
Gain (loss) on commodity derivatives	$ (20,289)	$ 12,519	$ 4,789

Gain (loss) incurred in hedging activities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5618551-113959

Name:	us-gaap_GainLossOnOilAndGasHedgingActivity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration