| **Commitments and Contingencies (Narrative) (Details) (USD $)** | 12 Months Ended | 9 Months Ended | 12 Months Ended |
|-----------------------------------------------------------------|-----------------|----------------|-----------------|
||
| **Operating Leases as Lessee**                                  |            |           |            |   |   |   |
| Rental costs                                                    | $ 46,500,000    | $ 37,400,000   | $ 36,300,000    |   |   |   |
| **Capital Leases as Lessee**                                    |            |           |            |   |   |   |
| Capital lease term                                              | 14 years        |           |            |   |   |   |
| Capital lease obligations                                       | 98,600,000      |           |            |   |   |   |
| Expected increase in capital lease                              | 9,400,000       |           |            |   |   |   |
| **Self-Insurance**                                              |            |           |            |   |   |   |
| Coverage limit per incident                                     | 500,000         |           |            |   |   |   |
| Self insurance reserve                                          | 3,100,000       | 2,700,000      |            |   |   |   |
| Workers compensation self insurance coverage limit per incident | 500,000         |           |            |   |   |   |
| Workers compensation self insurance reserve                     | 3,700,000       | 2,400,000      |            |   |   |   |
| **Cable Service Rate Reregulation**                             |            |           |            |   |   |   |
| Percent of subscribers request for petition                     | 25.00%          |           |            |   |   |   |
| Percent of basic service subscribers                            | 7.00%           |           |            |   |   |   |
| **TERRA-Northwest**                                             |            |           |            |   |   |   |
| Construction and development costs                              |            |           |            |   |   | 10,000,000 |
| **AWN Member Distribution Adjustment**                          |            |           |            |   |   |   |
| Preferential adjustment maximum                                 |            |           |            | $ 21,800,000 | $ 21,800,000 |   |

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Business Combination, Preferential Adjustment Maximum
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| - Definition
Capital Lease, Term
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| - Definition
Percent of Basic Service Subscribers
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Percent of Subscribers Request for Petition
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| - Definition
Self Insurance, Health Care, Maximum Coverage Per Incident
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| - Definition
Carrying amount (including both current and noncurrent portions) of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, arising from healthcare related claims.
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| - Definition
Workers Compensation, Coverage Floor Per Incident
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| - Definition
Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.
+ References
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| - Definition
The increase during the period in capital lease obligations due to entering into new capital leases.
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The aggregate costs related to construction and development services during the reporting period.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.
+ References
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount (including both current and noncurrent portions) of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, typically arising from workmen's compensation-type of incidents and personal injury to nonemployees from accidents on the entity's property.
+ References
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