Basis of Presentation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jan. 01, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Antidilutive options	616,800	1,934,300	649,300	2,597,600
Stock options
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Antidilutive options				654,200
Accounting Standards Update 2016-16
Organization, Consolidation and Presentation of Financial Statements [Abstract]
New accounting pronouncement, cumulative effect of change on prepaid income taxes and retained earnings					$ (19.9)