| **Income Taxes (Tables)**                              | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
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| **Income Tax Disclosure [Abstract]**                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| Schedule of Components of Income Tax Expense (Benefit) | Income tax expense consists of the following (amounts in thousands): Years Ended December 31, 2013 2012 2011Deferred tax expense:     Federal taxes$9,267 10,318 6,264State taxes1,690 1,770 1,141 $10,957 12,088 7,405                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Schedule of Effective Income Tax Rate Reconciliation   | Total income tax expense differed from the “expected” income tax expense determined by applying the statutory federal income tax rate of 35% as follows (amounts in thousands): Years Ended December 31, 2013 2012 2011“Expected” statutory tax expense$14,939 7,437 4,500Impact of non-controlling interest attributable to non-tax paying entity(7,977) — —State income taxes, net of federal expense1,690 1,770 1,141Income tax effect of nondeductible entertainment expenses1,045 777 737Income tax effect of nondeductible lobbying expenses369 298 327Income tax effect of nondeductible officer compensation824 1,718 758Other, net67 88 (58) $10,957 12,088 7,405                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Schedule of Deferred Tax Assets and Liabilities        | The tax effects of temporary differences that give rise to significant portions of deferred tax assets and liabilities at December 31, 2013 and 2012 are summarized below (amounts in thousands): 2013 2012Current deferred tax assets, net of current deferred tax liability:   Net operating loss carryforwards$30,344 3,952Compensated absences, accrued for financial reporting purposes2,956 2,605Workers compensation and self-insurance health reserves, principally due to accrual for financial reporting purposes1,688 1,357Accounts receivable, principally due to allowance for doubtful receivables1,154 1,319Deferred compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes104 32Deferred revenue for financial reporting purposes2,673 2,734Other834 898Total current deferred tax assets$39,753 12,897Long-term deferred tax assets:   Net operating loss carryforwards$90,589 116,034Deferred revenue for financial reporting purposes35,506 36,316Alternative minimum tax credits1,895 1,895Deferred compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes2,556 2,543Asset retirement obligations in excess of amounts recognized for tax purposes4,930 6,680Share-based compensation expense for financial reporting purposes in excess of amounts recognized for tax purposes1,860 1,675Other4,335 3,353Total long-term deferred tax assets141,671 168,496Long-term deferred tax liabilities:   Plant and equipment, principally due to differences in depreciation212,719 233,530Intangible assets49,761 58,627Flow-through entity deferred tax items40,667 —Total long-term deferred tax liabilities303,147 292,157Net long-term deferred tax liabilities$161,476 123,661 |
| Summary of Operating Loss Carryforwards                | Our tax net operating loss carryforwards are summarized below by year of expiration (amounts in thousands):Years ending December 31,Federal State2020$39,969 38,954202129,614 28,987202214,081 13,78820233,968 3,9032024722 —2025737 —2026150 —20271,010 —202839,879 39,715202948,370 47,5582031110,933 109,37620335,031 4,927Total tax net operating loss carryforwards$294,464 287,208                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |

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| - Definition
Tabular disclosure of the components of income tax expense attributable to continuing operations for each year presented including, but not limited to: current tax expense (benefit), deferred tax expense (benefit), investment tax credits, government grants, the benefits of operating loss carryforwards, tax expense that results from allocating certain tax benefits either directly to contributed capital or to reduce goodwill or other noncurrent intangible assets of an acquired entity, adjustments of a deferred tax liability or asset for enacted changes in tax laws or rates or a change in the tax status of the entity, and adjustments of the beginning-of-the-year balances of a valuation allowance because of a change in circumstances that causes a change in judgment about the realizability of the related deferred tax asset in future years.
+ References
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| - Definition
Tabular disclosure of the components of net deferred tax asset or liability recognized in an entity's statement of financial position, including the following: the total of all deferred tax liabilities, the total of all deferred tax assets, the total valuation allowance recognized for deferred tax assets.
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Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319
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| - Definition
Tabular disclosure of the reconciliation using percentage or dollar amounts of the reported amount of income tax expense attributable to continuing operations for the year to the amount of income tax expense that would result from applying domestic federal statutory tax rates to pretax income from continuing operations.
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| - Definition
Tabular disclosure of pertinent information, such as tax authority, amounts, and expiration dates, of net operating loss carryforwards, including an assessment of the likelihood of utilization.
+ References
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