| **Financial Instruments (Tables)**                            | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
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| **Fair Value Disclosures [Abstract]**                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Fair Value, by Balance Sheet Grouping                         | The carrying amounts and approximate fair values of our financial instruments at December 31, 2013 and 2012 follow (amounts in thousands): December 31,2013 December 31,2012 Carrying Amount Fair Value Carrying Amount Fair ValueCurrent and long-term debt$1,047,980 1,058,431 877,051 899,414                                                                                                                                                                                                                                                                                                                                                                                                        |
| Fair Value Assets and Liabilities Measured on Recurring Basis | Assets measured at fair value on a recurring basis as of December 31, 2013 and 2012 are as follows (amounts in thousands): Fair Value Measurement at Reporting Date UsingDecember 31, 2013 AssetsQuoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3)Deferred compensation plan assets (mutual funds)$2,183 — —Total assets at fair value$2,183 — —      December 31, 2012 Assets     Deferred compensation plan assets (mutual funds)$1,758 — —Total assets at fair value$1,758 — — |

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| - Definition
Tabular disclosure of the fair value of financial instruments, including financial assets and financial liabilities, and the measurements of those instruments, assets, and liabilities.
+ References
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| - Definition
Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).
+ References
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