CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Revenues	$ 86,766	$ 72,579	[1]
Costs and expenses:
Cost of revenues	40,453	29,212
Sales and marketing	23,830	23,837
Research and development	12,626	13,120
General and administrative	11,392	11,893
Change in fair value of escrowed shares and contingent consideration, net	7,350	(2,585)
Total costs and expenses	95,651	75,477
Loss from operations	(8,885)	(2,898)
Interest expense	(3,308)
Other income (expense), net	938	127
Loss before income taxes	(11,255)	(2,771)
Provision for (benefit from) income taxes	102	(97)
Net loss	$ (11,357)	$ (2,674)
Net loss per share, basic and diluted	$ (0.12)	$ (0.03)
Weighted-average number of common shares used in computing net loss per share, basic and diluted	92,711	87,490

[1] As noted above, prior period amounts have not been adjusted under the modified retrospective method.