Borrowings - Assets Pledged as Collateral (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Schedule of Borrowings [Line Items]
Outstanding borrowings	$ 997,702,000	$ 709,787,000
Aggregate fair value of loans purchased and held by UAWT	1,010,421,000	252,477,000
Restricted cash	110,056,000	204,633,000
Variable Interest Entity, Primary Beneficiary
Schedule of Borrowings [Line Items]
Restricted cash	13,147,000	79,561,000
ULT Warehouse Credit Facility | Revolving Credit Facility | Variable Interest Entity, Primary Beneficiary
Schedule of Borrowings [Line Items]
Outstanding borrowings	163,773,000	48,030,000
ULT Warehouse Credit Facility | Revolving Credit Facility | Variable Interest Entity, Primary Beneficiary | Asset Pledged as Collateral
Schedule of Borrowings [Line Items]
Aggregate outstanding principal of loans pledged as collateral	228,895,000	76,865,000
Aggregate fair value of loans purchased and held by UAWT	256,024,000	142,687,000
Restricted cash	8,547,000	76,256,000
UAWT Warehouse Credit Facility | Revolving Credit Facility | Variable Interest Entity, Primary Beneficiary
Schedule of Borrowings [Line Items]
Outstanding borrowings	172,679,000	$ 0
Aggregate outstanding principal of loans pledged as collateral	221,847,000
Aggregate fair value of loans purchased and held by UAWT	216,539,000
Restricted cash	$ 843,000