| **Consolidated Statement of Cash Flows Supplemental Disclosures ( Non-cash investing and financing activities) (Details) (USD $)In Thousands, unless otherwise specified** | 12 Months Ended |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Consolidated Statements of Cash Flows Supplemental Disclosures [Abstract]**                                                                                              |            |   |   |
| Non-cash additions for purchases of property and equipment                                                                                                                 | $ 9,010         | $ 7,233 | $ 7,622 |
| Asset retirement obligation additions to property and equipment                                                                                                            | 660             | 613 | 1,253 |
| Deferred compensation distribution denominated in shares                                                                                                                   | 511             | 0 | 0 |
| Asset retirement obligation reductions to property and equipment for revisions to previous estimates                                                                       | 0               | 294 | 0 |
| Assets acquired in acquisition                                                                                                                                             | $ 0             | $ 0 | $ 480 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of asset retirement obligations incurred during the period.
+ References
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Future cash outflow to pay for purchases of fixed assets that have occurred.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of assets that an Entity acquires in a noncash (or part noncash) acquisition that are not presented as a separate disclosure or not otherwise listed in the existing taxonomy. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The value of the noncash (or part noncash) consideration given (for example, liability, equity) in a transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of a transaction not resulting in cash receipts or cash payments in the period.
+ References
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| X                                                                                                                                                                        |
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