Bank call loans - Schedule of Bank Call Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Bank Call Loans [Abstract]
Year-end balance	$ 252,100	$ 0
Weighted interest rate (at end of year) (as a percent)	5.12%	0.00%
Maximum balance (at any month-end)	$ 288,200	$ 131,900
Average amount outstanding (during the year)	$ 167,691	$ 49,387
Average interest rate (during the year) (as a percent)	5.44%	4.20%