| **Goodwill and Other Intangibles (Details) (USD $)**           | 3 Months Ended  | 6 Months Ended |                 |
|----------------------------------------------------------------|-----------------|----------------|-----------------|
||
| **Indefinite-lived Intangible Assets by Segment [Line Items]** |            |           |            |   |   |
| Goodwill                                                       | $ 6,337,719,000 |           | $ 6,337,719,000 |   | $ 6,337,719,000 |
| **Other Intangibles:**                                         |            |           |            |   |   |
| Other intangibles                                              | 2,656,803,000   |           | 2,656,803,000   |   | 2,657,086,000 |
| Less: Accumulated amortization                                 | (1,287,868,000) |           | (1,287,868,000) |   | (1,114,347,000) |
| Total other intangibles, net                                   | 1,368,935,000   |           | 1,368,935,000   |   | 1,542,739,000 |
| Amortization expense                                           | 87,000,000      | 98,500,000     | 174,000,000     | 245,500,000 |   |
| Frontier Legacy Properties [Member]                            |            |           |            |   |   |
| **Other Intangibles:**                                         |            |           |            |   |   |
| Amortization expense                                           |            |           |            | 10,900,000 |   |
| Customer base [Member]                                         |            |           |            |   |   |
| **Other Intangibles:**                                         |            |           |            |   |   |
| Other intangibles                                              | 2,427,648,000   |           | 2,427,648,000   |   | 2,427,648,000 |
| Customer base [Member] | Residential customer list [Member]    |            |           |            |   |   |
| **Other Intangibles:**                                         |            |           |            |   |   |
| Estimated useful life                                          |            |           | 9 years         |   |   |
| Customer base [Member] | Business customer list [Member]       |            |           |            |   |   |
| **Other Intangibles:**                                         |            |           |            |   |   |
| Estimated useful life                                          |            |           | 12 years        |   |   |
| Software licenses [Member]                                     |            |           |            |   |   |
| **Other Intangibles:**                                         |            |           |            |   |   |
| Other intangibles                                              | 105,019,000     |           | 105,019,000     |   | 105,019,000 |
| Amortization expense                                           |            |           |            | 38,300,000 |   |
| Trade name and license [Member]                                |            |           |            |   |   |
| **Other Intangibles:**                                         |            |           |            |   |   |
| Other intangibles                                              | 124,136,000     |           | 124,136,000     |   | 124,419,000 |
| East [Member]                                                  |            |           |            |   |   |
| **Indefinite-lived Intangible Assets by Segment [Line Items]** |            |           |            |   |   |
| Goodwill                                                       | 2,003,574,000   |           | 2,003,574,000   |   |   |
| West [Member]                                                  |            |           |            |   |   |
| **Indefinite-lived Intangible Assets by Segment [Line Items]** |            |           |            |   |   |
| Goodwill                                                       | 1,300,534,000   |           | 1,300,534,000   |   |   |
| Central [Member]                                               |            |           |            |   |   |
| **Indefinite-lived Intangible Assets by Segment [Line Items]** |            |           |            |   |   |
| Goodwill                                                       | 1,815,498,000   |           | 1,815,498,000   |   |   |
| National [Member]                                              |            |           |            |   |   |
| **Indefinite-lived Intangible Assets by Segment [Line Items]** |            |           |            |   |   |
| Goodwill                                                       | $ 1,218,113,000 |           | $ 1,218,113,000 |   |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
+ References
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The net carrying amount as of the balance sheet date of other indefinite-lived and finite-lived intangible assets that are not separately presented on the statement of financial position.
+ References
No definition available.
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