Borrowings - Asset-backed Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Current balance	$ 1,780,005	$ 2,387,674
Loans receivable at fair value	2,962,352	3,175,449
Asset-backed borrowings at amortized cost	581,468	0
Pledged Asset
Debt Instrument [Line Items]
Loans receivable at fair value	580,102
Oportun CL Trust 2023-A
Debt Instrument [Line Items]
Asset-backed borrowings at amortized cost	195,057
Oportun CL Trust 2023-A \| Pledged Asset
Debt Instrument [Line Items]
Loans receivable at fair value	197,390
Other Asset Backed Borrowings
Debt Instrument [Line Items]
Asset-backed borrowings at amortized cost	386,411
Other Asset Backed Borrowings \| Pledged Asset
Debt Instrument [Line Items]
Loans receivable at fair value	382,712
Secured Debt
Debt Instrument [Line Items]
Initial note amount issued	2,754,412	2,754,412
Current balance	1,780,005	2,387,674
Secured Debt \| Initial Collateral
Debt Instrument [Line Items]
Collateral balance	2,834,687	2,834,687
Secured Debt \| Current Collateral
Debt Instrument [Line Items]
Collateral balance	1,976,039	2,706,900
Secured Debt \| Oportun Issuance Trust (Series 2022-3)
Debt Instrument [Line Items]
Initial note amount issued	300,000	300,000
Current balance	$ 145,732	$ 285,218
Weighted average interest rate	9.34%	8.43%
Secured Debt \| Oportun Issuance Trust (Series 2022-3) \| Initial Collateral
Debt Instrument [Line Items]
Collateral balance	$ 310,993	$ 310,993
Secured Debt \| Oportun Issuance Trust (Series 2022-3) \| Current Collateral
Debt Instrument [Line Items]
Collateral balance	165,079	301,967
Secured Debt \| Oportun Issuance Trust (Series 2022-2)
Debt Instrument [Line Items]
Initial note amount issued	400,000	400,000
Current balance	$ 135,825	$ 313,689
Weighted average interest rate	8.46%	7.03%
Secured Debt \| Oportun Issuance Trust (Series 2022-2) \| Initial Collateral
Debt Instrument [Line Items]
Collateral balance	$ 410,212	$ 410,212
Secured Debt \| Oportun Issuance Trust (Series 2022-2) \| Current Collateral
Debt Instrument [Line Items]
Collateral balance	156,027	344,218
Secured Debt \| Oportun Issuance Trust (Series 2022-A)
Debt Instrument [Line Items]
Initial note amount issued	400,000	400,000
Current balance	$ 390,755	$ 380,313
Weighted average interest rate	5.44%	5.44%
Debt term	2 years	2 years
Secured Debt \| Oportun Issuance Trust (Series 2022-A) \| Initial Collateral
Debt Instrument [Line Items]
Collateral balance	$ 410,211	$ 410,211
Secured Debt \| Oportun Issuance Trust (Series 2022-A) \| Current Collateral
Debt Instrument [Line Items]
Collateral balance	415,448	414,293
Secured Debt \| Oportun Issuance Trust (Series 2021-C)
Debt Instrument [Line Items]
Initial note amount issued	500,000	500,000
Current balance	$ 459,212	$ 435,951
Weighted average interest rate	2.47%	2.48%
Debt term	3 years	3 years
Secured Debt \| Oportun Issuance Trust (Series 2021-C) \| Initial Collateral
Debt Instrument [Line Items]
Collateral balance	$ 512,762	$ 512,762
Secured Debt \| Oportun Issuance Trust (Series 2021-C) \| Current Collateral
Debt Instrument [Line Items]
Collateral balance	519,612	518,929
Secured Debt \| Oportun Issuance Trust (Series 2021-B)
Debt Instrument [Line Items]
Initial note amount issued	500,000	500,000
Current balance	$ 466,317	$ 432,123
Weighted average interest rate	2.05%	2.05%
Debt term	3 years	3 years
Secured Debt \| Oportun Issuance Trust (Series 2021-B) \| Initial Collateral
Debt Instrument [Line Items]
Collateral balance	$ 512,759	$ 512,759
Secured Debt \| Oportun Issuance Trust (Series 2021-B) \| Current Collateral
Debt Instrument [Line Items]
Collateral balance	519,115	519,182
Secured Debt \| Oportun Funding XIV, LLC (Series 2021-A)
Debt Instrument [Line Items]
Initial note amount issued	375,000	375,000
Current balance	$ 182,164	$ 348,046
Weighted average interest rate	1.78%	1.79%
Debt term	2 years	2 years
Secured Debt \| Oportun Funding XIV, LLC (Series 2021-A) \| Initial Collateral
Debt Instrument [Line Items]
Collateral balance	$ 383,632	$ 383,632
Secured Debt \| Oportun Funding XIV, LLC (Series 2021-A) \| Current Collateral
Debt Instrument [Line Items]
Collateral balance	200,758	389,740
Secured Debt \| Oportun Funding XIII, LLC (Series 2019-A)
Debt Instrument [Line Items]
Initial note amount issued	279,412	279,412
Current balance	$ 0	$ 192,334
Weighted average interest rate	0.00%	3.46%
Debt term	3 years	3 years
Secured Debt \| Oportun Funding XIII, LLC (Series 2019-A) \| Initial Collateral
Debt Instrument [Line Items]
Collateral balance	$ 294,118	$ 294,118
Secured Debt \| Oportun Funding XIII, LLC (Series 2019-A) \| Current Collateral
Debt Instrument [Line Items]
Collateral balance	$ 0	$ 218,571

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