Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) State Customer Agreement Segment Center	Dec. 31, 2016 USD ($) Segment	Dec. 31, 2015 USD ($)
Business And Summary Of Significant Accounting Policies [Line Items]
Number of distribution centers | Center	27
Number of states in which products are distributed | State	41
Allowance for doubtful accounts days	90 days
Inventory valuation LIFO method	87.00%	91.00%
First-In, First-Out cost higher than LIFO valuation	$ 15.1	$ 13.4
Company recorded depreciation expense	3.7	3.0	$ 2.9
Shipping and handling products cost	$ 34.0	$ 30.2	$ 28.8
Percentage of consolidated revenues of company's top ten clients	42.00%
Number of major customers | Customer	10
Percentage of employees represented under collective bargaining agreements	12.00%
Number of collective bargaining agreements | Agreement	8
Percentage of employees covered under four expiring collective bargaining agreements	1.00%
Number of collective bargaining agreements expired in next year | Agreement	1
Aggregate number of reporting segment | Segment	1	1
Major Customer [Member]
Business And Summary Of Significant Accounting Policies [Line Items]
Total sales in percentage	14.00%	14.00%	13.00%
Maximum [Member]
Business And Summary Of Significant Accounting Policies [Line Items]
Original maturity of cash equivalents	All highly liquid interest-earning investments with an original maturity of three months or less at the date of purchase
Maximum [Member] | Building and Building Improvements [Member]
Business And Summary Of Significant Accounting Policies [Line Items]
Buildings and improvements lives	25 years
Maximum [Member] | Machinery and Equipment [Member]
Business And Summary Of Significant Accounting Policies [Line Items]
Buildings and improvements lives	10 years
Minimum [Member] | Building and Building Improvements [Member]
Business And Summary Of Significant Accounting Policies [Line Items]
Buildings and improvements lives	3 years
Minimum [Member] | Machinery and Equipment [Member]
Business And Summary Of Significant Accounting Policies [Line Items]
Buildings and improvements lives	3 years