Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)	Jan. 01, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reporting segment operated | Segment	1
Accrued capital expenditures	$ 1.2	$ 1.0
Number of days allowed to the customer to return product for expiration or damage	30 days
Long Term Incentive Plans [Member]
Summary Of Significant Accounting Policies [Line Items]
LTIP estimated unrecognized compensation expense	$ 35.4
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effects of accounting changes			$ 64.1