CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (unaudited) - USD ($) shares in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenue		$ 109,392,000	$ 90,941,000	$ 211,690,000	$ 179,206,000
Cost of revenue	[1],[2]	21,688,000	21,009,000	42,460,000	40,953,000
Gross profit		87,704,000	69,932,000	169,230,000	138,253,000
Operating expenses:
Research and development	[1]	34,225,000	26,571,000	67,208,000	53,128,000
Sales and marketing	[1],[2]	56,025,000	42,578,000	108,061,000	84,669,000
General and administrative	[1]	24,170,000	21,339,000	47,492,000	43,271,000
Total operating expenses		114,420,000	90,488,000	222,761,000	181,068,000
Loss from operations		(26,716,000)	(20,556,000)	(53,531,000)	(42,815,000)
Interest expense		2,304,000	2,422,000	4,603,000	5,508,000
Other non-operating (income) expense, net		(119,000)	102,000	196,000	(1,134,000)
Loss before income taxes		(28,901,000)	(23,080,000)	(58,330,000)	(47,189,000)
Provision for (benefit from) income taxes		336,000	(156,000)	554,000	(15,000)
Net loss		$ (29,237,000)	$ (22,924,000)	$ (58,884,000)	$ (47,174,000)
Net loss per share, basic and diluted		$ (0.20)	$ (0.17)	$ (0.40)	$ (0.34)
Weighted-average shares used in computing basic and diluted net loss per share		146,242	138,777	145,467	137,844

[1] ⁽¹⁾       Includes stock-based compensation, net of amounts capitalized as follows:       Three Months Ended June 30,   Six Months Ended June 30,   (in thousands)   2021   2020   2021   2020   Cost of revenue   $ 1,580   $ 1,047   $ 3,062   $ 2,007   Research and development     10,313     7,496     19,810     13,953   Sales and marketing     6,414     4,841     12,192     9,184   General and administrative     7,266     6,087     14,108     11,829   Stock-based compensation, net of amounts capitalized   $ 25,573   $ 19,471   $ 49,172   $ 36,973  

[2] ⁽²⁾      Includes amortization of acquisition intangible assets as follows:       Three Months Ended June 30,   Six Months Ended June 30,   (in thousands)   2021   2020   2021   2020   Cost of revenue   $ 1,477   $ 2,003   $ 2,967   $ 4,013   Sales and marketing     1,117     1,355     2,250     2,713   Amortization of acquisition intangible assets   $ 2,594   $ 3,358   $ 5,217   $ 6,726