Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014 Project	Jun. 30, 2013 Project	Jun. 30, 2014 Source Method Project	Jun. 30, 2013 Project	Dec. 31, 2013
Accounting Policies [Abstract]
Number of product revenue sources			2
Unbilled receivables	$ 43.9		$ 43.9		$ 52.9
Number of projects	12	11	16	15
Percentage of total revenues	5.00%	6.00%	8.00%	12.00%
Percentage of product revenues	6.00%	7.00%	10.00%	14.00%
Number of service revenue sources			3