| **Intangible Assets Intangible Assets (Details) - USD ($) $ in Millions**                      | 3 Months Ended | 12 Months Ended |
|------------------------------------------------------------------------------------------------|----------------|-----------------|
||
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Gross Carrying Amount                                                                          |           | $ 2,138         | $ 1,930 | $ 2,138 |   |
| Accumulated Amortization                                                                       |           | 363             | 388 | 363 |   |
| Net                                                                                            |           | 1,775           | 1,542 | 1,775 |   |
| Amortization expense related to intangible assets                                              |           |            | 167 | 68 | $ 59 |
| Non-cash impairment charge related to intangibles                                              | $ 367          |            | 367 | 46 | $ 0 |
| **Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]** |           |            |   |   |   |
| 2017                                                                                           |           |            | 161 |   |   |
| 2018                                                                                           |           |            | 148 |   |   |
| 2019                                                                                           |           |            | 144 |   |   |
| 2020                                                                                           |           |            | 130 |   |   |
| 2021                                                                                           |           |            | 130 |   |   |
| Thereafter                                                                                     |           |            | 829 |   |   |
| Total                                                                                          |           | 1,775           | 1,542 | 1,775 |   |
| Harris CapRock Communications                                                                  |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Non-cash impairment charge related to intangibles                                              | 367            |            |   |   |   |
| Critical Networks | Harris CapRock Communications                                              |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Non-cash impairment charge related to intangibles                                              |           |            | 367 |   |   |
| Critical Networks | Impairment of goodwill and others assets                                   |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Non-cash impairment charge related to intangibles                                              |           | 38              |   |   |   |
| Critical Networks | Impairment of goodwill and others assets | Harris CapRock Communications   |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Non-cash impairment charge related to intangibles                                              | $ 44           |            |   |   |   |
| Exelis                                                                                         |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Amortization expense related to intangible assets                                              |           |            | 132 | 11 |   |
| Customer Relationships                                                                         |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Gross Carrying Amount                                                                          |           | 1,718           | 1,527 | 1,718 |   |
| Accumulated Amortization                                                                       |           | 203             | 195 | 203 |   |
| Net                                                                                            |           | 1,515           | 1,332 | 1,515 |   |
| Developed Technology                                                                           |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Gross Carrying Amount                                                                          |           | 253             | 244 | 253 |   |
| Accumulated Amortization                                                                       |           | 67              | 86 | 67 |   |
| Net                                                                                            |           | 186             | 158 | 186 |   |
| Contract Backlog                                                                               |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Gross Carrying Amount                                                                          |           | 49              | 55 | 49 |   |
| Accumulated Amortization                                                                       |           | 48              | 55 | 48 |   |
| Net                                                                                            |           | 1               | 0 | 1 |   |
| Trade Names                                                                                    |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Gross Carrying Amount                                                                          |           | 81              | 64 | 81 |   |
| Accumulated Amortization                                                                       |           | 22              | 20 | 22 |   |
| Net                                                                                            |           | 59              | 44 | 59 |   |
| Other                                                                                          |           |            |   |   |   |
| **Finite-Lived Intangible Assets [Line Items]**                                                |           |            |   |   |   |
| Gross Carrying Amount                                                                          |           | 37              | 40 | 37 |   |
| Accumulated Amortization                                                                       |           | 23              | 32 | 23 |   |
| Net                                                                                            |           | $ 14            | $ 8 | $ 14 |   |

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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.
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| - Definition
Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.
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| - Definition
Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
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| - Definition
Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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| - Definition
Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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| - Definition
Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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| - Definition
Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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| - Definition
Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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| - Definition
Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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| - Definition
Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
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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.
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| - Definition
Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
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| - Definition
Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.
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