Variable Interest Entities - Assets and Liabilities (Details) - USD ($) $ in Thousands		Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Assets	[1]	$ 1,917,018		$ 1,820,455
Liabilities	[1]	1,159,947		1,013,377
Net Assets		757,071	$ 876,504	807,078	$ 716,096	$ 320,590	$ 300,252
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets		627,869		342,025
Liabilities		212,013		49,314
Net Assets		415,856		292,711
Variable Interest Entity, Not Primary Beneficiary | Securitizations and other
Variable Interest Entity [Line Items]
Assets		121,454		217,321
Liabilities		83,779		160,248
Net Assets		37,675		57,073
Maximum Exposure to Losses		$ 11,913		$ 15,503

[1] The following table presents information on assets and liabilities related to variable interest entities (“VIEs”) that are consolidated by Upstart Holdings, Inc. at December 31, 2021 and June 30, 2022. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. The holders of the beneficial interests do not have recourse to the general credit of Upstart Holdings, Inc. The assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs and exclude intercompany balances that eliminate in consolidation. December 31,June 30,20212022AssetsCash $7,700 $1,326 Restricted cash79,561 11,460 Loans (at fair value)245,972 607,830  Other assets (includes $7,571 and $4,310 at fair value as of December 31, 2021 and June 30, 2022, respectively) 8,792 7,253 Total assets$342,025 $627,869 LiabilitiesBorrowings48,536 208,123 Other liabilities 778 3,890 Total liabilities49,314 212,013 Total net assets$292,711 $415,856