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Stock-Based Compensation - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]        
Stock-based compensation expense $ 19 $ 24 $ 59 $ 78
Income tax benefit recognized $ 0 $ 0 $ 0 $ 0