Description of Business and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Description of Business and Significant Accounting Policies	Description of Business and Significant Accounting Policies Description of Business Upstart Holdings, Inc. and its subsidiaries (together “Upstart”, the “Company”, “we”, or “our”) apply modern data science and technology to the process of originating consumer credit. The Company helps originate credit, including personal and auto loans, by providing lending partners with access to a proprietary, cloud-based, artificial intelligence lending marketplace. As the Company’s technology continues to improve and additional lending partners adopt the Upstart platform, consumers benefit from improved access to affordable and frictionless credit. The Company currently operates in the United States and is headquartered in San Mateo, California and Columbus, Ohio. The Company’s fiscal year ends on December 31. Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements included in our Annual Report on Form 10-K. Certain prior period amounts have been reclassified or disaggregated where appropriate to conform to the current period presentation of such amounts. In the opinion of management, the accompanying financial statements reflect all adjustments, which include only normal recurring adjustments, necessary to state fairly the Company’s financial position, results of operations, comprehensive income (loss) and cash flows for the periods presented, but are not necessarily indicative of the results of operations to be anticipated of any future annual or interim periods. Certain information and disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to rules and regulations of the Securities and Exchange Commission. Accordingly, the information included in this Quarterly Report on Form 10-Q should be read in conjunction with the consolidated financial statements and accompanying notes included in our Annual Report on Form 10-K for the year ended December 31, 2022. Use of Estimates The preparation of the unaudited condensed consolidated financial statements in conformity with GAAP requires that management make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions made in the accompanying condensed consolidated financial statements, which Management believes are critical in understanding and evaluating the Company’s reported financial results include: (i) fair value determinations; (ii) stock-based compensation; (iii) consolidation of VIEs; and (iv) the evaluation for impairment of goodwill and acquired intangible assets. The Company bases its estimates on various factors it believes to be reasonable under the circumstances. Actual results could differ from those estimates and such differences could affect the results of operations reported in future periods. Derivative Financial Instruments The Company evaluates its contracts and financial instruments to determine if these contracts and instruments or their parts meet the definition of derivatives in accordance with the requirements of FASB Accounting Codification (ASC) 815, Derivatives and Hedging. Derivatives are recorded on the condensed consolidated balance sheets at fair value with changes in the value recorded in earnings as part of interest expense or fair value adjustments in the condensed consolidated statements of operations and comprehensive income (loss). The Company does not employ derivatives for trading or speculative purposes and has no derivatives classified as accounting hedges. Refer to “Note 4. Derivative Financial Instruments” for further details. Recently Adopted Accounting Pronouncements On January 1, 2023, the Company adopted Accounting Standards Update (“ASU”) 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which was issued by the Financial Accounting Standards Board (“FASB”) in October 2021. The new guidance requires contract assets and contract liabilities acquired in a business combination to be recognized and measured by the acquirer on the acquisition date in accordance with ASC 606, Revenue from Contracts with Customers, as if it had originated the contracts. Under the previous business combinations guidance, such assets and liabilities are recognized by the acquirer at fair value on the acquisition date. The ASU will be applied prospectively to business combinations occurring after the adoption date. The adoption of this new standard did not have an impact on the Company's condensed consolidated financial statements or related disclosures. Recently Issued Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting followed by ASU 2021-01, Reference Rate Reform, Scope issued in January 2021. ASU 2020-04 and ASU 2021-01 provide temporary optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions that reference the London Interbank Offered Rate or another reference rate expected to be discontinued because of reference rate reform, if certain criteria are met. The optional guidance in ASU 2020-04 and ASU 2021-01 and ASU 2022-06 is effective for a limited period of time through December 31, 2024 and may be applied prospectively to contract modifications and hedging relationships. The Company does not expect the adoption of this guidance will have a material impact on the Company’s condensed consolidated financial statements or related disclosures.