Condensed Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue:
Revenue from fees, net	$ 313,982	$ 116,170
Interest income and fair value adjustments, net	(3,846)	5,175
Total revenue	310,136	121,345
Operating expenses:
Sales and marketing	133,449	49,376
Customer operations	48,407	17,388
Engineering and product development	49,991	18,988
General, administrative, and other	43,456	20,019
Total operating expenses	275,303	105,771
Income from operations	34,833	15,574
Other Nonoperating Expense	(2,122)	(5,251)
Net income before income taxes	32,711	10,323
Provision for income taxes	19	221
Net income	$ 32,692	$ 10,102
Net income (loss) per share attributable to Upstart Holdings, Inc. common stockholders, basic (in dollars per share)	$ 0.39	$ 0.14
Net income (loss) per share attributable to Upstart Holdings, Inc. common stockholders, diluted (in dollars per share)	$ 0.34	$ 0.11
Weighted-average number of shares outstanding used in computing net income (loss) per share attributable to Upstart Holdings, Inc. common stockholders, basic (in shares)	84,230,445	73,629,122
Weighted-average number of shares outstanding used in computing net income (loss) per share attributable to Upstart Holdings, Inc. common stockholders, diluted (in shares)	95,457,776	91,449,571