| **Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions**                 | 12 Months Ended |        |
|-----------------------------------------------------------------------------------------|-----------------|--------|
||
| **Valuation and allowance roll forward**                                                |            |   |   |   |
| Beginning balance, January 1                                                            | $ 78            | $ 49   |   |   |
| Ending balance, December 31                                                             | 69              | 78     | $ 49 |   |
| Accounting Standards Update 2016-13                                                     |            |   |   |   |
| **Valuation and allowance roll forward**                                                |            |   |   |   |
| Cumulative effect of change in accounting for credit loss as of January 1, 2020, pretax |            | 0      | 3 | $ 0 |
| Allowance for doubtful receivables                                                      |            |   |   |   |
| **Valuation and allowance roll forward**                                                |            |   |   |   |
| Beginning balance, January 1                                                            | 22              | 8      | 6 |   |
| Additions charged to costs and expenses                                                 | 14              | 19     | 8 |   |
| Deductions                                                                              | (20)            | (8)    | (6) |   |
| Ending balance, December 31                                                             | 16              | 22     | 8 |   |
| Deferred tax valuation allowance                                                        |            |   |   |   |
| **Valuation and allowance roll forward**                                                |            |   |   |   |
| Beginning balance, January 1                                                            | 56              | 41     | 0 |   |
| Additions charged to costs and expenses                                                 | 0               | 15     | 55 |   |
| Deductions                                                                              | (3)             | 0      | (14) |   |
| Ending balance, December 31                                                             | $ 53            | $ 56   | $ 41 |   |

| X                                                                                                                                                                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Increase to allowance through retained earnings for ASU 2016-13, pretax
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of valuation and qualifying accounts and reserves.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column B)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column E)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of increase in valuation and qualifying accounts and reserves from charge to cost and expense.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column C)(1)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of decrease in valuation and qualifying accounts and reserves.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column D)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690
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| X                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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