| **Discontinued Operations - Depreciation, Amortization, Capital Expenditures, and Significant Operating and Investing Noncash Items (Details) - Critical Networks - CapRock - Discontinued Operations, Held-for-sale - USD ($) $ in Millions** | 3 Months Ended | 6 Months Ended |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]**                                                                                                              |           |           |   |   |
| Depreciation and amortization                                                                                                                                                                                                                  | $ 3            | $ 12           | $ 11 | $ 25 |
| Capital expenditures                                                                                                                                                                                                                           | 2              | 4              | 4 | 8 |
| Impairment of goodwill and other assets                                                                                                                                                                                                        | $ 0            | $ 367          | $ 0 | $ 367 |

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| - Definition
Disposal Group, Including Discontinued Operations, Capital Expenditures
+ References
No definition available.
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| - Definition
Disposal Group, Including Discontinued Operations, Impairment of Goodwill and Other Assets
+ References
No definition available.
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| - Definition
Amount of depreciation and amortization expense attributable to disposal group, including, but not limited to, discontinued operation.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 5B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760
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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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| X                                                                                                                                                                               |
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