CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenue	$ 2,085	$ 2,541	$ 1,901
Cost of revenue	977	947	443
Gross profit	1,108	1,594	1,458
Operating expenses:
Sales and marketing	1,102	1,708	1,463
Product development	208	222	74
General and administrative	165	295	65
Total operating expenses	1,475	2,225	1,602
Loss from operations	(367)	(631)	(144)
Other income (expense), net:
Interest and other income (expense), net	16	(2)	19
Remeasurement of redeemable convertible preferred stock warrant liability		(110)	(3)
Loss before provision for income taxes	(351)	(743)	(128)
Provision for income taxes	10	2	1
Net loss	(361)	(745)	(129)
Deemed dividend to redeemable convertible preferred stockholders			(7)
Net loss attributable to common stockholders	$ (361)	$ (745)	$ (136)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.57)	$ (5.87)	$ (1.31)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	629	127	104