Commitments and Contingencies - Information Regarding the Company's Insurance Coverage (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
2009
Product Liability Contingency [Line Items]
Insurance Coverage	$ 10.0
Deductible Amount	1.0
Remaining Insurance Coverage	10.0
2010
Product Liability Contingency [Line Items]
Insurance Coverage	10.0
Deductible Amount	1.0
Remaining Insurance Coverage	10.0
2011
Product Liability Contingency [Line Items]
Insurance Coverage	10.0
Deductible Amount	1.0
Remaining Insurance Coverage	10.0
Jan - Jun 2012
Product Liability Contingency [Line Items]
Insurance Coverage	7.0
Deductible Amount	1.0
Remaining Insurance Coverage	7.0
Jul - Dec 2012
Product Liability Contingency [Line Items]
Insurance Coverage	12.0
Deductible Amount	1.0
Remaining Insurance Coverage	12.0
2013
Product Liability Contingency [Line Items]
Insurance Coverage	12.0
Deductible Amount	1.0
Remaining Insurance Coverage	12.0
2014
Product Liability Contingency [Line Items]
Insurance Coverage	11.0
Deductible Amount	4.0
Remaining Insurance Coverage	11.0
2015
Product Liability Contingency [Line Items]
Insurance Coverage	10.0
Deductible Amount	5.0
Remaining Insurance Coverage	10.0
2016
Product Liability Contingency [Line Items]
Insurance Coverage	10.0
Deductible Amount	5.0
Remaining Insurance Coverage	10.0
2017
Product Liability Contingency [Line Items]
Insurance Coverage	10.0
Deductible Amount	5.0
Remaining Insurance Coverage	10.0
2018
Product Liability Contingency [Line Items]
Insurance Coverage	10.0
Deductible Amount	5.0
Remaining Insurance Coverage	$ 10.0