Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue:
Revenue from fees, net		$ 907,272	$ 801,275	$ 228,600
Interest income		105,580	20,634	26,408
Interest expense		(10,843)	(3,274)	(8,026)
Fair value and other adjustments	[1]	(159,565)	29,954	(13,566)
Total interest income and fair value adjustments, net		(64,828)	47,314	4,816
Total revenue		842,444	848,589	233,416
Operating expenses:
Sales and marketing		345,776	333,453	99,659
Customer operations		187,994	117,579	37,581
Engineering and product development		237,247	133,999	38,802
General, administrative, and other		185,290	122,677	45,609
Total operating expenses		956,307	707,708	221,651
Income (loss) from operations		(113,863)	140,881	11,765
Other income (expense), net		9,473	(5,174)	5,549
Expense on warrants and convertible notes, net		(4,684)	(1,976)	(11,364)
Net income (loss) before income taxes		(109,074)	133,731	5,950
(Benefit) provision for income taxes		(409)	(1,712)	371
Net income (loss) before attribution to noncontrolling interests		(108,665)	135,443	5,579
Net loss attributable to noncontrolling interests		0	0	(404)
Net income (loss) before attribution to noncontrolling interests		$ (108,665)	$ 135,443	$ 5,983
Net income (loss) attributable to Upstart Holdings, Inc. common stockholders per share, basic (in dollars per share)		$ (1.31)	$ 1.73	$ 0
Net income (loss) attributable to Upstart Holdings, Inc. common stockholders per share, diluted (in dollars per share)		$ (1.31)	$ 1.43	$ 0
Weighted-average number of shares outstanding used in computing net income per share (loss) attributable to Upstart Holdings, Inc. common stockholders, basic (in shares)		82,771,268	78,106,359	17,513,670
Weighted-average number of shares outstanding used in computing net income (loss) per share attributable to Upstart Holdings, Inc. common stockholders, diluted (in shares)		82,771,268	94,772,641	17,513,670

[1] Includes $1,014 from related parties expense and $4,238 of related parties fair value adjustments for the year ended December 31, 2020. There were no related party balances for the years ended year ended December 31, 2021 and 2022.