Secured borrowings - Collateral Pledged (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Asset pledged as collateral without right
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	$ 3,710,913
Secured borrowings
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	3,710,913	$ 3,320,583
Borrowings under credit facilities and other financing arrangements | Loans and finance receivables
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	285,963	212,512
Borrowings under credit facilities and other financing arrangements | Asset pledged as collateral without right | Loans and finance receivables
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	285,963
Borrowings under repurchase agreements | Securities sold under agreements to repurchase
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	3,424,950	3,108,071
Borrowings under repurchase agreements | Asset pledged as collateral without right | Securities sold under agreements to repurchase
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	3,424,950
Real estate acquired in settlement of loans | Borrowings under repurchase agreements | Securities sold under agreements to repurchase
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	131,180	160,455
Loans, held for sale | Borrowings under credit facilities and other financing arrangements | Loans and finance receivables
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	24,186	43,365
Loans, held for sale | Borrowings under repurchase agreements | Securities sold under agreements to repurchase
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	579,866	9,349
Loans, net | Borrowings under credit facilities and other financing arrangements | Loans and finance receivables
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	261,777	169,147
Loans, net | Borrowings under repurchase agreements | Securities sold under agreements to repurchase
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	2,117,106	2,560,725
Mortgage backed securities | Borrowings under repurchase agreements | Securities sold under agreements to repurchase
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	80,093	20,770
Mortgage backed securities | Borrowings under repurchase agreements | Asset pledged as collateral without right | Securities sold under agreements to repurchase
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	596,798
Retained interest in assets of consolidated VIEs | Borrowings under repurchase agreements | Securities sold under agreements to repurchase
Collateral pledged
Total Loans, in consolidated VIEs, before allowance for loan losses	$ 516,705	$ 356,772