Revenue Recognition (Disaggregation) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Gathering and transportation lease revenues	$ 12,318
Total revenues	18,536	$ 25,807
Natural gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	473	2,779
Oil
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,462	11,350
Natural gas liquid
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	595	467
Gathering and transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,688	11,211
Production
Disaggregation of Revenue [Line Items]
Total revenues	4,530
Production \| Natural gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	473	2,779
Production \| Oil
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,462	11,350
Production \| Natural gas liquid
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	595	467
Midstream
Disaggregation of Revenue [Line Items]
Gathering and transportation lease revenues	12,318
Total revenues	14,006
Midstream \| Gathering and transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,688	$ 11,211

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Aggregate revenue during the period related to oil and gas business activities.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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