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Employee Benefit Plans - Additional Information (Detail)
$ in Millions
 12 Months Ended
Dec. 31, 2017
USD ($)
Employees
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Compensation Related Costs Disclosure [Line Items]      
Expenses for defined-contribution plans $ 64 $ 66 $ 95
Net periodic benefit cost 1 $ 5 $ 5
Defined benefit plan, expected future benefit payments in year five $ 33    
Expected years of defined benefit plans 5 years    
Expected future benefit amounts to pay, total $ 324    
United States [Member]      
Compensation Related Costs Disclosure [Line Items]      
Number of U.S retirees and spouses participate in defined benefit health care plans | Employees 1,950    
Number of U.S. employees participate in defined benefit health care plans | Employees 40