New Accounting Pronouncements - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($) Business_Units	Sep. 30, 2017 USD ($)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Number of business units inconsistent with revenue recognition | Business_Units	2
Accounting Standards Update 2016-18 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
New accounting pronouncements or adoption of new standard resulted a (decrease) increase in net cash provided by operating activities	$ (0.4)	$ 4.2
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Future minimum cash commitments under operating leases	$ 200.0