Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenue (net of a $0 and $0 reduction of revenue during the three months ended September 30, 2012 and 2011 and net of a $0 and $2,500 reduction of revenue during the nine months ended September 30, 2012 and 2011 relating to a common stock warrant)	$ 30,768	$ 20,019	$ 81,488	$ 50,636
Cost of revenue	9,135	5,371	23,869	14,903
Gross profit	21,633	14,648	57,619	35,733
Operating expenses:
Sales and marketing	18,624	11,531	52,283	32,244
Research and development	4,101	2,670	10,625	7,608
General and administrative	6,600	3,439	18,346	10,577
Amortization of certain acquired intangible assets	251	0	488	0
Total operating expenses	29,576	17,640	81,742	50,429
Loss from operations	(7,943)	(2,992)	(24,123)	(14,696)
Other income (expense):
Interest income	0	8	0	15
Interest expense	(121)	(43)	(358)	(797)
Change in fair value of preferred stock warrant liabilities	0	0	0	(42,559)
Withdrawn secondary offering expense	0	(555)	0	(555)
Other, net	139	(643)	(42)	(220)
Other income (expense), net	18	(1,233)	(400)	(44,116)
Loss before income tax benefit (provision)	(7,925)	(4,225)	(24,523)	(58,812)
Income tax benefit (provision)	298	(52)	550	(132)
Net loss	(7,627)	(4,277)	(23,973)	(58,944)
Accretion of redeemable preferred stock	0	0	0	(5,208)
Net loss attributable to common stockholders	$ (7,627)	$ (4,277)	$ (23,973)	$ (64,152)
Net loss per share attributable to common stockholders - basic and diluted (in usd per share)	$ (0.15)	$ (0.09)	$ (0.48)	$ (1.74)
Weighted average common shares outstanding, basic and diluted (in shares)	50,163	48,018	49,755	36,868