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Employee Benefit Plans - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]      
Employee waiting period after hire to participate in the defined contribution plans 90 days    
Employee maximum contribution towards defined contribution plans as percentage of annual compensation 50.00%    
Employee maximum contribution towards defined contribution plans as percentage of annual incentive plan bonus 80.00%    
Percentage of contribution upon eligibility for non union employees hired after threshold period 3.00%    
Employer's match in cash of non-union employee contributions on first specified percentage of eligible compensation 100.00%    
First percentage of eligible compensation on which specified percentage of non-union employee contribution is matched by the employer in cash 3.00%    
Employer's match in cash of non-union employee contributions on next specified percentage of eligible compensation 50.00%    
Next percentage of eligible compensation on which specified percentage of non-union employee contribution is matched by the employer in cash 3.00%    
Employer maximum match of non-union employee contribution on eligible compensation 4.50%    
Defined contribution plans expense $ 92 $ 88 $ 80
Accrued benefit liabilities 18 19  
Pension Plans [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Combined accumulated benefit obligation of pension plans 154 141  
Plan assets of pension plans 150 136  
Unfunded benefit obligation 4 5  
Other Postretirement Plans [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Unfunded benefit obligation $ 14 $ 14