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Employee Benefits - Overview of the accumulated benefit obligation, fair value of plan assets, funded status and net amount recognized for U.S. and Canadian Other Post-Retirement Benefits (Details) - Other Post-Retirement Benefits - USD ($)
$ in Millions
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Accumulated projected benefit obligation $ 103 $ 91
Fair value of plan assets 16 14
Funded status (87) (77)
Unrecognized prior-service credit (1) (1)
Unrecognized loss 3 (6)
Net amount recognized $ (85) $ (84)