Employee Retirement and Profit Sharing Plans - Summary of Assumptions Used to Determine Benefit Obligations (Detail) - Pension Plan	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Weighted average discount rate (as a percent)	3.69%	4.29%
Rate of compensation increase (as a percent)	3.70%	3.70%