Borrowings - Assets Pledged as Collateral (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Schedule of Borrowings [Line Items]
Outstanding borrowings	$ 869,373,000	$ 709,787,000
Restricted cash	123,990,000	204,633,000
Variable Interest Entity, Primary Beneficiary
Schedule of Borrowings [Line Items]
Restricted cash	11,460,000	79,561,000
ULT Warehouse Credit Facility | Revolving Credit Facility | Variable Interest Entity, Primary Beneficiary
Schedule of Borrowings [Line Items]
Outstanding borrowings	109,951,000	48,030,000
ULT Warehouse Credit Facility | Revolving Credit Facility | Variable Interest Entity, Primary Beneficiary | Asset Pledged as Collateral
Schedule of Borrowings [Line Items]
Outstanding principal balance	169,373,000	76,865,000
Aggregate fair value of loans purchased and held	181,536,000	142,687,000
Restricted cash	6,366,000	76,256,000
UAWT Warehouse Credit Facility | Revolving Credit Facility | Variable Interest Entity, Primary Beneficiary
Schedule of Borrowings [Line Items]
Outstanding borrowings	98,172,000	$ 0
Outstanding principal balance	120,628,000
Aggregate fair value of loans purchased and held	131,183,000
Restricted cash	$ 662,000