Variable interest entities and securitization activities - Consolidated VIE Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets
Cash and cash equivalents	$ 138,532	$ 147,399	$ 192,970
Restricted cash	30,063	48,146	$ 41,032
Loans, held for sale, at fair value	81,599	123,735
Other assets	265,578	183,533
Total Assets	12,441,217	11,620,977
Liabilities
Accounts payable and other accrued liabilities	171,445	153,614
Total Liabilities	9,794,455	9,722,382
Consolidated VIEs
Assets
Loans, net	6,611,325	6,311,698
Liabilities
Secured borrowings	5,068,453	4,903,350
Reportable Legal Entities | Consolidated VIEs
Assets
Cash and cash equivalents	671	997
Restricted cash	93,240	77,062
Loans, net	6,611,325	6,311,698
Preferred equity investments	108,423	108,423
Other assets	83,486	54,580
Total Assets	6,897,145	6,552,760
Liabilities
Secured borrowings	5,068,453	4,903,350
Due to third parties	2,944	3,727
Accounts payable and other accrued liabilities	34
Total Liabilities	$ 5,071,431	$ 4,907,077