CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue		$ 79,317	$ 65,205	$ 223,097	$ 186,392
Cost of revenue	[1],[2]	19,626	23,213	56,203	58,967
Gross profit		59,691	41,992	166,894	127,425
Operating expenses:
Research and development	[2]	22,718	51,765	65,931	85,997
Sales and marketing	[1],[2]	30,926	34,309	86,665	71,609
General and administrative	[2]	20,992	50,391	61,294	76,809
Restructuring		0	0	(66)	33
Total operating expenses		74,636	136,465	213,824	234,448
Loss from operations		(14,945)	(94,473)	(46,930)	(107,023)
Interest expense		3,572	7,496	10,878	22,181
Other non-operating income (expense), net		887	(219)	3,441	132
Loss before income taxes		(17,630)	(102,188)	(54,367)	(129,072)
Provision for (benefit from) income taxes		(1,320)	174	(1,802)	470
Net loss		$ (16,310)	$ (102,362)	$ (52,565)	$ (129,542)
Net loss per share, basic and diluted		$ (0.12)	$ (0.99)	$ (0.40)	$ (1.27)
Weighted-average shares used in computing basic and diluted net loss per share		133,417	103,096	130,434	101,984

[1] Includes amortization of acquisition intangible assets as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Cost of revenue $1,557 $488 $3,448 $1,464 Sales and marketing 964 565 2,267 1,773 Amortization of acquisition intangible assets $2,521 $1,053 $5,715 $3,237

[2] Includes stock-based compensation, net of amounts capitalized as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Cost of revenue $718 $6,472 $2,805 $7,776 Research and development 5,468 37,490 15,863 43,903 Sales and marketing 2,918 14,496 8,714 16,411 General and administrative 5,678 40,354 17,665 48,014 Stock-based compensation, net of amounts capitalized $14,782 $98,812 $45,047 $116,104