XML 108 R97.htm IDEA: XBRL DOCUMENT v3.5.0.2
Retirement and Deferred Compensation Plans - Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Detail) - Postretirement Benefits [Member]
$ in Millions
12 Months Ended
Dec. 31, 2015
USD ($)
Defined Benefit Plan Disclosure [Line Items]  
Effect on service and interest cost components, 1% Increase $ (1)
Effect on postretirement benefit obligation, 1% Increase (4)
Effect on service and interest cost components, 1% Decrease (1)
Effect on postretirement benefit obligation, 1% Decrease $ (3)