Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			1 Months Ended
	Sep. 30, 2012 Cost of revenues	Sep. 30, 2011 Cost of revenues	Sep. 30, 2012 Cost of revenues	Sep. 30, 2011 Cost of revenues	Sep. 30, 2012 Finite-lived Intangible Assets	Sep. 30, 2011 Finite-lived Intangible Assets	Sep. 30, 2012 Finite-lived Intangible Assets	Sep. 30, 2011 Finite-lived Intangible Assets	Jan. 31, 2012 Intellectual Property Rights	Apr. 30, 2012 Sonar Limited
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired									$ 800,000
Additional finite lived intangible assets										7,100,000
Amortization expense	$ 300,000	$ 32,000	$ 700,000	$ 100,000	$ 600,000	$ 32,000	$ 1,100,000	$ 100,000