Business Acquisition - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended							3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended		0 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Developed technology	Sep. 30, 2012 Customer relationships	Sep. 30, 2012 Non-compete agreements	Sep. 30, 2012 Domains/trademark/tradenames	Sep. 30, 2012 Restricted Stock Shares	Sep. 30, 2012 General and administrative expense	Sep. 30, 2012 General and administrative expense	Sep. 30, 2012 Sonar Limited	Sep. 30, 2012 Sonar Limited	Apr. 05, 2012 Sonar Limited Employee	Apr. 05, 2012 Sonar Limited Common Stock
Business Acquisition [Line Items]
Business acquisition, cash paid														$ 12,500,000
Common stock issued, business acquisition (in shares)									31,164						15,530
Business acquisition, stock issued (in usd)									700,000					300,000
Reasons for business acquisition, size of acquiree target client by number of employees														500
Cash consideration and shares issued placed in escrow (in usd)														1,800,000
Identified intangible assets amortization period					4 years	4 years	2 years 6 months	2 years
Identified intangible assets combined weighted average useful life			3 years 9 months 18 days
Acquisition related costs										0	700,000
Net revenue attributable to Sonar	30,768,000	20,019,000	81,488,000	50,636,000								700,000	1,100,000
Net loss attributable to Sonar	(7,627,000)	(4,277,000)	(23,973,000)	(58,944,000)								(800,000)	(1,800,000)
Amortization of acquired intangible assets attributable to Sonar												$ 500,000	$ 900,000
Vesting period									2 years