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Summary of Significant Accounting Policies Other (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Accounts Receivable Additional Disclosures [Abstract] |  |  |  |
Receivables Collection Period |  | 2 months |  |
Allowance for Doubtful Accounts Receivable |  | $ 1,700 | $ 1,100 |
Concentration of Credit Risk and Major Customers [Abstract] |  |  |  |
Number of individual entities within groups of entities under common ownership that represent more than 10 percent of total production revenue |  | 0 |  |
Number of Derivative Counterparties |  | 10 |  |
Revenues [Abstract] |  |  |  |
Revenue Receipt, Days After Sale, Low End of Range |  | 30 days |  |
Revenue Receipt, Days After Sale, High End of Range |  | 90 days |  |
Income Statement [Abstract] |  |  |  |
Marketed gas system revenue |  | $ 0 | 9,485 | $ 24,897
Marketed gas system expense |  | $ 0 | $ 13,922 | $ 24,460
Customer Concentration Risk [Member] | Oil And Gas Sales Revenue [Member] | Major Customer One [Member] |  |  |  |
Concentration of Credit Risk and Major Customers [Abstract] |  |  |  |
Entity-Wide Revenue, Major Customer, Percentage | [1] | 18.00% | 21.00% | 19.00%
Customer Concentration Risk [Member] | Oil And Gas Sales Revenue [Member] | Unnamed Major Customer One with Related Entities [Member] |  |  |  |
Concentration of Credit Risk and Major Customers [Abstract] |  |  |  |
Entity-Wide Revenue, Major Customer, Percentage | [2] | 15.00% | 10.00% | 14.00%
Customer Concentration Risk [Member] | Oil And Gas Sales Revenue [Member] | Unnamed Major Customer Two with Related Entities [Member] |  |  |  |
Concentration of Credit Risk and Major Customers [Abstract] |  |  |  |
Entity-Wide Revenue, Major Customer, Percentage | [2] | 8.00% | 11.00% | 9.00%
Minimum [Member] |  |  |  |
Asset Retirement Obligation [Abstract] |  |  |  |
Fair Value Assumptions, Risk Free Interest Rate |  | 5.50% |  |
Maximum [Member] |  |  |  |
Asset Retirement Obligation [Abstract] |  |  |  |
Fair Value Assumptions, Risk Free Interest Rate |  | 12.00% |  |
Oil and Gas Properties [Member] |  |  |  |
Impairment of Proved, Unproved, and Other Properties [Abstract] |  |  |  |
Period of New York Mercantile Exchange Strip Pricing Used for Price Forecast |  | 5 years |  |
Property, Plant and Equipment, Other Types [Member] | Minimum [Member] |  |  |  |
Property, Plant and Equipment [Abstract] |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives |  | 3 |  |
Property, Plant and Equipment, Other Types [Member] | Maximum [Member] |  |  |  |
Property, Plant and Equipment [Abstract] |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives |  | 30 |  |
Revolving Credit Facility [Member] | Line of Credit [Member] |  |  |  |
Line of Credit Facility [Abstract] |  |  |  |
Revolving credit facility | [3] | $ 0 | $ 202,000 |
[1] | This major customer is the operator of the Company’s outside-operated Eagle Ford shale program, in which the Company entered into various marketing agreements with during 2013, whereby the Company is subject to certain gathering, transportation, and processing throughput commitments for up to 10 years pursuant to each contract. Because the Company shares with its operator the risk of non-performance by its counterparty purchasers, the Company has included its operator as a major customer in the table above. Several of the operator’s counterparty purchasers under these contracts are also direct purchasers of the Company’s production from other areas. As of December 31, 2016, the Company’s outside-operated Eagle Ford shale assets were classified as held for sale.
[2] | In the aggregate these groups of entities under common ownership represent more than 10 percent of total production revenue for the period(s) shown, however, none of the entities comprising either group individually represented more than 10 percent of the Company’s production revenue.
[3] | Unamortized deferred financing costs attributable to the credit facility are presented as a component of other noncurrent assets on the accompanying balance sheets and totaled $5.9 million and $4.9 million as of December 31, 2016, and 2015, respectively.

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