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Compensation Plans Non Stock-Based Compensation (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Net Profits Plan [Member] |  |  |
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] |  |  |
Minimum percentage of oil and gas wells, costs recovered for payment to employees from Net Profit Plan | 100.00% |  |
Percentage of future net cash flow received by participants from Net Profit Plan | 10.00% |  |
Percentage of future net cash flow received by participants from Net Profit Plan increased to | 20.00% |  |
Percentage of oil and gas wells costs recovered for additional payment employees from Net Profit Plan | 200.00% |  |
Cash payments made or accrued related to operations | $ 63 | $ (54) | $ 6,608
Cash payments made or accrued related to divestitures | 0 | 2,753 | 24,349
Total net settlements | $ 63 | 2,699 | 30,957
401K Plan [Member] |  |  |
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] |  |  |
Defined Contribution Plan, maximum annual contributions per employee, percent | 60.00% |  |
Defined Contribution Plan, employer matching contribution, percent of employees' gross pay | 6.00% |  |
Defined Contribution Plan, matching contributions | $ 4,900 | $ 4,500 | $ 5,400
Prior to 2014 [Member] | 401K Plan [Member] |  |  |
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] |  |  |
Defined Contribution Plan, employer matching contribution, percent of match | 100.00% |  |
After 2014 [Member] | 401K Plan [Member] |  |  |
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] |  |  |
Defined Contribution Plan, employer matching contribution, percent of match | 150.00% |  |

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- Definition Represents the minimum percentage of total costs required to be recovered for payment of net profit plan. + References No definition available. + Details
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- Definition Represents the percentage of future net cash payment to employees from the net profit plan. + References No definition available. + Details
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- Definition Represents the percentage of future net cash payment to employees from the net profit plan. + References No definition available. + Details
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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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