Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) Project	Sep. 30, 2015 Project	Sep. 30, 2016 USD ($) Project Source Method	Sep. 30, 2015 Project	Dec. 31, 2015 USD ($)
Accounting Policies [Abstract]
Number of product revenue sources | Method			2
Unbilled receivables | $	$ 66.2		$ 66.2		$ 70.8
Number of projects | Project	4	9	10	14
Percentage of total revenues	12.00%	17.00%	14.00%	16.00%
Percentage of product revenues	14.00%	22.00%	17.00%	20.00%
Number of service revenue sources | Source			3