Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue:
Revenue from fees, net		$ 167,590	$ 146,755	$ 436,190	$ 407,585
Interest income, interest expense, and fair value adjustments, net:
Interest income	[1]	40,845	37,692	144,899	116,923
Interest expense	[1]	(10,818)	(9,414)	(33,002)	(20,828)
Fair value and other adjustments	[1]	(35,477)	(40,476)	(130,523)	(130,430)
Total interest income, interest expense, and fair value adjustments, net		(5,450)	(12,198)	(18,626)	(34,335)
Total revenue		162,140	134,557	417,564	373,250
Operating expenses:
Sales and marketing		43,229	33,042	111,337	88,371
Customer operations		39,302	36,914	117,394	114,301
Engineering and product development		64,887	54,941	186,431	222,986
General, administrative, and other		59,874	53,505	170,508	156,616
Total operating expenses		207,292	178,402	585,670	582,274
Loss from operations		(45,152)	(43,845)	(168,106)	(209,024)
Other income, net		5,078	3,540	8,993	11,334
Gain on debt extinguishment		33,361	0	33,361	0
Net loss before income taxes		(6,713)	(40,305)	(125,752)	(197,690)
Provision for income taxes		45	10	74	44
Net loss		$ (6,758)	$ (40,315)	$ (125,826)	$ (197,734)
Net loss per share, basic (in dollars per share)		$ (0.07)	$ (0.48)	$ (1.42)	$ (2.38)
Net loss per share, diluted (in dollars per share)		$ (0.07)	$ (0.48)	$ (1.42)	$ (2.38)
Weighted-average number of shares outstanding used in computing net loss per share, basic (in shares)		90,119,481	84,404,966	88,534,495	83,158,146
Weighted-average number of shares outstanding used in computing net loss per share, diluted (in shares)		90,119,481	84,404,966	88,534,495	83,158,146

[1] Balances for the three and nine months ended September 30, 2023 and 2024 include amounts related to the consolidated securitization. Refer to “Note 2. Revenue” for details.