Fair Value of Assets and Liabilities - Sensitivity Analysis of Debt Securities Available-for-Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Sensitivity Analysis of Debt Securities Available-for-Sale [Line Items]
Total securities available for sale	$ 795,669	$ 345,702
Other asset-backed securities related to Structured Program transactions
Sensitivity Analysis of Debt Securities Available-for-Sale [Line Items]
Total securities available for sale	31,062
Discount rates
100 basis point increase	(369)
200 basis point increase	(735)
Expected loss rates
10% increase	(523)
20% increase	(1,058)
Expected prepayment rates
10% increase	(190)
20% increase	$ (425)
Other asset-backed securities related to Structured Program transactions | Weighted- Average
Sensitivity Analysis of Debt Securities Available-for-Sale [Line Items]
Expected weighted-average life (in years)	1 year 6 months