Marketplace Revenue - Components of Marketplace Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Gain on sales of loans	$ 8,572	$ 23,554	$ 35,918	$ 76,983
Net fair value adjustments	(41,366)	(619)	(80,222)	24,277
Total marketplace revenue	60,886	173,837	239,303	560,187
Origination fees
Disaggregation of Revenue [Line Items]
Revenue	60,912	127,142	202,444	398,487
Servicing fees
Disaggregation of Revenue [Line Items]
Revenue	$ 32,768	$ 23,760	$ 81,163	$ 60,440