Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) Project	Jun. 30, 2015 Project	Jun. 30, 2016 USD ($) Project Source Method	Jun. 30, 2015 Project	Dec. 31, 2015 USD ($)
Accounting Policies [Abstract]
Number of product revenue sources | Method			2
Unbilled receivables | $	$ 62.5		$ 62.5		$ 70.8
Number of projects | Project	6	10	10	13
Percentage of total revenues	16.00%	17.00%	15.00%	16.00%
Percentage of product revenues	19.00%	21.00%	19.00%	19.00%
Number of service revenue sources | Source			3