Marketplace Revenue - Components of Marketplace Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Gain on sales of loans	$ 47,839	$ 95,335	$ 70,116
Net fair value adjustments	(134,114)	8,503	3,986
Total marketplace revenue	291,484	683,626	578,580
Origination fees
Disaggregation of Revenue [Line Items]
Revenue	279,146	499,179	416,839
Servicing fees
Disaggregation of Revenue [Line Items]
Revenue	$ 98,613	$ 80,609	$ 87,639