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Stock-Based Compensation - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share Based Compensation Percentage In Annual Base Salary, Min 50.00%    
Deferred Compensation Arrangement with Individual, Shares Issued 40,000 34,000 36,000
Maximum number of shares reserved for grant of awards 22,500,000    
Shares available for grant under the plan 5,300,000    
Aggregate Intrinsic Value - Exercised $ 1 $ 8 $ 21
Share-based Payment Arrangement, Expense 22 24 10
Share-based Payment Arrangement, Expense, after Tax $ 17 $ 18 $ 7