|**Net Income (Loss) Per Common Share (Tables)**       | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
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|**Earnings Per Share [Abstract]**                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Calculations For Basic And Diluted Earnings Per Share | The table shows calculations for basic and diluted earnings per share:(In millions, except per share data)Three months ended September 30,Nine months ended September 30,2023202220232022Numerator:Net income (loss)—basic and diluted$(99)$(416)$660$(1,500)Denominator:Basic weighted-average common shares outstanding156.9158.0157.0159.3Effect of share-based awards:Stock options——0.7—Nonvested shares——0.5—Diluted weighted-average shares156.9158.0158.2159.3Earnings (loss) per share:Basic$(0.63)$(2.63)$4.20$(9.42)Diluted$(0.63)$(2.63)$4.17$(9.42)Number of anti-dilutive share-based awards2.42.31.31.9
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|(In millions, except per share data)                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|                                                      | 2023                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Numerator:                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Net income (loss)—basic and diluted                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Denominator:                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Basic weighted-average common shares outstanding      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Effect of share-based awards:                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Stock options                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Nonvested shares                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Diluted weighted-average shares                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Earnings (loss) per share:                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Basic                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Diluted                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Number of anti-dilutive share-based awards            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
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X- ReferencesNo definition available.
+ Details**Name:**
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duration X- DefinitionTabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations.
+ ReferencesReference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 260 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482662/260-10-50-1
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