CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenue		$ 88,265	$ 68,641
Cost of revenue	[1],[2]	19,944	17,530
Gross profit		68,321	51,111
Operating expenses:
Research and development	[1]	26,557	20,806
Sales and marketing	[1],[2]	42,091	26,050
General and administrative	[1]	21,932	20,556
Restructuring		0	(66)
Total operating expenses		90,580	67,346
Loss from operations		(22,259)	(16,235)
Interest expense		3,086	3,659
Other non-operating (income) expense, net		(1,236)	(1,979)
Loss before income taxes		(24,109)	(17,915)
Provision for (benefit from) income taxes		141	(138)
Net loss		$ (24,250)	$ (17,777)
Net loss per share, basic and diluted		$ (0.18)	$ (0.14)
Weighted-average shares used in computing basic and diluted net loss per share		136,911	126,786

[1]   ^{(1) Includes stock-based compensation, net of amounts capitalized as follows:}       Three Months Ended March 31,   (in thousands)   2020     2019   Cost of revenue   $ 960     $ 1,096   Research and development     6,457       4,766   Sales and marketing     4,343       2,780   General and administrative     5,742       6,469   Stock-based compensation, net of amounts capitalized   $ 17,502     $ 15,111    

[2]   ^{(2) Includes amortization of acquisition intangible assets as follows:}       Three Months Ended March 31,   (in thousands)   2020     2019   Cost of revenue   $ 2,010     $ 488   Sales and marketing     1,358       537   Amortization of acquisition intangible assets   $ 3,368     $ 1,025