Long Term Debt - Schedule of Debt Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total debt	$ 729,372	$ 626,583	$ 449,393
Convertible Senior Notes
Debt Instrument [Line Items]
Total debt	287,926	286,800
Securitization debt of consolidated VIEs at fair value
Debt Instrument [Line Items]
Total debt	167,716	314,095
Securitization debt of consolidated VIEs at amortized cost
Debt Instrument [Line Items]
Total debt	242,295
Financing of Beneficial Interest in Securizations
Debt Instrument [Line Items]
Total debt	21,125	15,378
Junior Subordinated Debentures
Debt Instrument [Line Items]
Total debt	$ 10,310	$ 10,310