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Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2021
Jun. 30, 2021
Mar. 31, 2021
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Earnings $ 19 $ 21 $ (8) $ 27 $ 36 $ (194) $ 32 $ (131)  
Joint Ventures [Member] | Other Assets [Member]                  
Investment balance 6           6   $ 9
Joint Ventures [Member] | Investment Income and Other, Net [Member]                  
Earnings $ 1     $ 5     $ 3 $ 12