|**Schedule V. Valuation and Qualifying Accounts**                     | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
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|**SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Schedule V. Valuation and Qualifying Accounts                         | SCHEDULE V.  VALUATION AND QUALIFYING ACCOUNTS(In millions)Balance at Beginning of PeriodCharged to Costs and ExpensesCharged to Other Accounts(1)DeductionsBalance at End of PeriodYear ended December 31, 2019Deducted from assets:Allowance for doubtful accounts:Insurance and reinsurance receivables$71$(6)$—$(8)$57Year ended December 31, 2018Deducted from assets:Allowance for doubtful accounts:Insurance and reinsurance receivables$73$4$—$(6)$71Year ended December 31, 2017Deducted from assets:Allowance for doubtful accounts:Insurance and reinsurance receivables$83$(1)$—$(9)$73(1)    Amount includes effects of foreign currency translation.
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|(In millions)                                                         | Balance at Beginning of Period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Year ended December 31, 2019                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Deducted from assets:                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Allowance for doubtful accounts:                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Insurance and reinsurance receivables                                 | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Year ended December 31, 2018                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Deducted from assets:                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Allowance for doubtful accounts:                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Insurance and reinsurance receivables                                 | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Year ended December 31, 2017                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Deducted from assets:                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Allowance for doubtful accounts:                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Insurance and reinsurance receivables                                 | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  

X- DefinitionThe entire disclosure for valuation and qualifying accounts and reserves.
+ ReferencesReference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12 -Subsection 09Reference 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) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690
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