Employee Retirement and Profit Sharing Plans - Summary of Assumptions Used to Determine Net Periodic Benefit Cost (Detail) - Pension Plan	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Effective discount rate for benefit obligations (as a percent)	4.29%	4.53%	4.08%
Effective rate for interest on benefit obligations (as a percent)	3.56%	3.76%	4.08%
Effective discount rate for service cost (as a percent)	4.51%	4.67%	4.08%
Effective rate for interest on service cost (as a percent)	3.91%	4.14%	4.08%
Expected return on assets (as a percent)	6.25%	6.75%	7.00%
Rate of compensation increase (as a percent)	3.70%	4.00%	4.00%