Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) Project	Jun. 30, 2014 Project	Jun. 30, 2015 USD ($) Project Method Source	Jun. 30, 2014 USD ($) Project	Dec. 31, 2014 USD ($)
Significant Accounting Policies [Line Items]
Number of product revenue sources | Method			2
Unbilled receivables	$ 77.6		$ 77.6		$ 68.0
Number of projects | Project	10	12	13	16
Percentage of total revenues	17.00%	5.00%	16.00%	8.00%
Percentage of product revenues	21.00%	6.00%	19.00%	10.00%
Number of service revenue sources | Source			3
Prepaid and Other Current Assets [Member]
Significant Accounting Policies [Line Items]
Prior period reclassification adjustment				$ 6.7