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Retirement and Deferred Compensation Plans - Components of Net Periodic Cost and Underlying Weighted Average Actuarial Assumptions Used for Pension and Postretirement Benefit Plans (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Pension Benefits [Member]      
Component of Net Periodic Benefit Costs      
Service cost $ 4 $ 5 $ 5
Interest cost 7 8 9
Expected return on assets (7) (8) (11)
Amortization of actuarial (gain) loss 1 2 1
Net periodic benefit cost $ 5 $ 7 $ 4
Weighted Average Assumptions used to determine Net Period Benefit Cost for the Years ended December 31      
Discount rate 3.90% 3.70% 4.60%
Salary increases 4.60% 4.60% 4.90%
Expected return on assets 4.10% 3.90% 5.60%
Postretirement Benefits [Member]      
Component of Net Periodic Benefit Costs      
Service cost $ 2 $ 2 $ 3
Interest cost 1 1 1
Amortization of actuarial (gain) loss (1)    
Curtailment (gain) loss     0
Net periodic benefit cost $ 2 $ 3 $ 4
Weighted Average Assumptions used to determine Net Period Benefit Cost for the Years ended December 31      
Discount rate 3.95% 3.62% 4.33%
Healthcare cost trend      
Initial 7.00% 7.00% 7.00%
Ultimate in 2025 5.00% 5.00% 5.00%