Revenue Recognition - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended
	Mar. 31, 2018	Jan. 01, 2018	Mar. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to opening retained earnings, net of tax			$ 2,888
Contract liability revenue recognized			6,300
Transaction price allocated to uncompleted contracts	$ 78,600		$ 78,600
Expected time of revenue recognition	Over the next 18 months
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to opening retained earnings, net of tax		$ 2,900