Borrowings - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule of Borrowings [Line Items]
Total payments due	$ 709,787	$ 62,681
Unamortized debt discount	(14,355)	(55)
Total borrowings	695,432	62,626
Term loan
Schedule of Borrowings [Line Items]
Total payments due	0	15,000
UNI credit facility | Revolving credit facility
Schedule of Borrowings [Line Items]
Total payments due	0	5,500
Warehouse credit facilities | Revolving credit facility
Schedule of Borrowings [Line Items]
Total payments due	48,030	34,994
Risk retention funding loans
Schedule of Borrowings [Line Items]
Total payments due	507	7,187
Convertible senior notes
Schedule of Borrowings [Line Items]
Total payments due	$ 661,250	$ 0