Marketplace Revenue - Components of Marketplace Revenue (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Gain on sales of loans		$ 70,116	$ 30,812	$ 67,716
Net fair value adjustments	[1]	3,986	(105,002)	(144,273)
Total marketplace revenue		578,580	245,314	646,735
Origination fees
Disaggregation of Revenue [Line Items]
Net Revenue		416,839	207,640	598,760
Servicing fees
Disaggregation of Revenue [Line Items]
Net Revenue		$ 87,639	$ 111,864	$ 124,532

[1] Prior period amounts have been reclassified to conform to the current period presentation. See “Notes to Consolidated Financial Statements – Note 1. Summary of Significant Accounting Policies” for additional information.