| **Long-Term Debt (Tables)**              | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
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| **Debt Disclosure [Abstract]**           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Schedule of Long-term Debt Instruments   | Long-term debt consists of the following at December 31, 2013 and 2012 (amounts in thousands): 2013 20122021 Notes (a)$325,000 325,0002019 Notes (b)425,000 425,000Senior Credit Facility (c)261,000 90,000Rural Utilities Service ("RUS") debt (d)39,425 38,997CoBank Mortgage note payable— 797Debt1,050,425 879,794Less unamortized discount paid on the 2019 Notes2,445 2,743Less current portion of long-term debt2,836 1,928Long-term debt, net$1,045,144 875,123                                                                                             |
| Debt Instrument Redemption               | If redeemed during the twelve month period commencing June 1 of the year indicated:Redemption Price2016103.375%2017102.250%2018101.125%2019 and thereafter100.000%The 2019 Notes are redeemable at our option, in whole or in part, on not less than thirty days nor more than sixty days notice, at the following redemption prices (expressed as percentages of principle amount), plus accrued and unpaid interest (if any) to the date of redemption:If redeemed during the twelve month period commencing November 15 of the year indicated:Redemption Price2014104.313%2015102.875%2016101.438%2017 and thereafter100.000% |
| Interest Margin                          | The interest rate on our Amended Senior Credit Facility is London Interbank Offered Rate (“LIBOR”) plus the following Applicable Margin set forth opposite each applicable Total Leverage Ratio below.    Total Leverage Ratio (as defined)Applicable Margin>=5.53.00%>=5.0 but <5.52.75%>=4.5 but <5.02.50%>=4.0 but <4.52.25%<4.02.00%                                                                                                                                                                                                                                 |
| Schedule of Maturities of Long-term Debt | Maturities of long-term debt as of December 31, 2013 are as follows (amounts in thousands):Years ending December 31, 2014$2,83620151,52820161,57320171,6202018262,6682019 and thereafter780,200 1,050,425Less unamortized discount paid on 2019 Notes2,445Less current portion of long-term debt2,836 $1,045,144                                                                                                                                                                                                                                                                                                  |

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Schedule of Interest Margin
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| - Definition
Tabular disclosure of debt instruments or arrangements with redemption features. Includes, but is not limited to, description of debt redemption features, percentage price at which debt can be redeemed by the issuer, and period start and end for debt maturity or redemption.
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| - Definition
Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.
+ References
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| - Definition
Tabular disclosure of the combined aggregate amount of maturities and sinking fund requirements for all long-term borrowings for each of the five years following the date of the latest balance sheet date presented.
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