Commitments and Contingencies Additional information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) MMcf	Sep. 30, 2016 USD ($)
Loss Contingencies [Line Items]
Transportation, gathering and processing expenses	$ 9,794	$ 5,048	$ 22,184	$ 13,554
Loss Contingency, Actions Taken by Court, Arbitrator or Mediator	A consent decree was signed by all parties on October 31, 2017 and is subject to a 30-day comment period in which it will be publicly published in the Federal Register. The consent decree provides that we will implement changes to our design, operation, and maintenance of most of our field-wide storage tank systems to enhance our emission management in the DJ Basin.  Agreed upon and planned efforts include, but are not limited to, vapor control system modifications and verification, increased inspection and monitoring, and installation of tank pressure monitors. We voluntarily included in the consent decree approximately 40 additional facilities associated with our pending acquisition of additional assets in the basin.  The three primary elements of the consent decree are: (i) fine/supplemental environmental projects ($1.5 million cash fine, plus $1 million in supplemental environmental projects); (ii) injunctive relief with an estimated cost of approximately $18 million, primarily representing capital enhancements to our operations; and (iii) mitigation with an estimated cost of $1.7 million.  Certain expenditures for the injunctive relief are believed to have been incurred in 2016 and 2017, with the remainder expected to be incurred over the next few years. We do not believe that the expenditures resulting from the settlement will have a material adverse effect on our consolidated financial statements. Although we believe the consent decree will be approved by the court following the comment period, this cannot be guaranteed.
First facilities agreement with midstream provider [Member]
Loss Contingencies [Line Items]
incremental volume commitment | MMcf			51.5
Utica Shale natural gas and Wattenberg Field crude oil [Member]
Loss Contingencies [Line Items]
Transportation, gathering and processing expenses	$ 2,600	$ 2,600	$ 7,400	$ 7,200