| **Summary of Significant Accounting Policies - Narrative (Details) (USD $)In Millions, unless otherwise specified** | 9 Months Ended |        |        | 3 Months Ended | 9 Months Ended |
|---------------------------------------------------------------------------------------------------------------------|----------------|--------|--------|----------------|----------------|
||
| **Accounting Policies [Line Items]**                                                                                |           |   |   |           |           |   |   |   |   |
| Number Of Segments                                                                                                  | 4              |   |   |           |           |   |   |   |   |
| Concentration Risk Number Of Employees                                                                              |           |   | 6,000  | 300            |           |   |   |   |   |
| concentration risk number of employees percentage                                                                   |           |   | 68.00% | 5.00%          |           |   |   |   |   |
| Goodwill                                                                                                            | $ 38           | $ 184  |   |           |           | $ 142 |   |   |   |
| Indefinite-Lived Intangible Assets (Excluding Goodwill)                                                             |           |   |   |           |           | 43 |   |   |   |
| Goodwill, Impairment Loss                                                                                           |           |   |   |           | 0              | 142 | 0 | 142 | 0 |
| Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)                                              |           |   |   |           | $ 0            | $ 7 | $ 0 | $ 7 | $ 0 |

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| - Definition
Concentration Risk Number Of Employees
+ References
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| - Definition
concentration risk number of employees percentage
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.
+ References
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| - Definition
Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.
+ References
No definition available.
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