Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) Project Source Method	Mar. 31, 2016 Project	Dec. 31, 2016 USD ($)
Accounting Policies [Abstract]
Number of product revenue sources | Method	2
Unbilled receivables | $	$ 55.6		$ 56.8
Number of projects | Project	6	9
Percentage of total revenues	12.00%	15.00%
Percentage of product revenues	16.00%	18.00%
Number of service revenue sources | Source	3