Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Project	Sep. 30, 2013 Project	Sep. 30, 2014 Source Method Project	Sep. 30, 2013 Project	Dec. 31, 2013
Accounting Policies [Abstract]
Number of product revenue sources			2
Unbilled receivables	$ 62.8		$ 62.8		$ 52.9
Number of projects	14	12	17	16
Percentage of total revenues	15.00%	15.00%	10.00%	13.00%
Percentage of product revenues	18.00%	18.00%	13.00%	15.00%
Number of service revenue sources			3