Variable interest entities and securitization activities - Consolidated VIE Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Assets
Cash and cash equivalents	$ 166,004		$ 59,863
Restricted cash	24,915		$ 43,736
Loans, held for sale, at fair value	584,072	$ 81,599
Other assets	315,772	300,175
Total Assets	12,043,532	12,441,217
Liabilities
Secured borrowings	2,198,272	2,102,075
Accounts payable and other accrued liabilities	193,896	207,481
Total Liabilities	9,535,289	9,794,455
Consolidated VIEs
Assets
Loans, net	6,342,684	6,611,325
Loans, held for sale	10,973
Liabilities
Secured borrowings	4,769,057	5,068,453
Reportable Legal Entities | Consolidated VIEs
Assets
Cash and cash equivalents	9	671
Restricted cash	44,607	93,240
Loans, net	6,342,684	6,611,325
Loans, held for sale	10,973
Preferred equity investments	106,548	108,423
Other assets	87,013	83,486
Total Assets	6,591,834	6,897,145
Liabilities
Secured borrowings	4,769,057	5,068,453
Due to third parties	2,780	2,944
Accounts payable and other accrued liabilities	1	34
Total Liabilities	$ 4,771,838	$ 5,071,431