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Asset Retirement Obligations (Tables)
12 Months Ended
Dec. 31, 2021
Asset Retirement Obligation Disclosure [Abstract]  
Changes in Carrying Values of Asset Retirement Obligations The following table reflects changes in the carrying values of AROs for the years ended December 31, 2021 and 2020:
December 31,
(In millions)20212020
Balance at beginning of year$60 $58 
Additional obligations incurred3 
Obligations settled(7)(7)
Change in estimate of obligations(1) 
Foreign currency translation effects(1)
Accretion expense12 
Balance at end of period$66 $60