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Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Income Tax Disclosure [Abstract]        
Provision (benefit) for income taxes $ 60 $ 29 $ (323) $ 37