Mortgage Loans - Allowance for loan losses (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ (403,000)	$ (4,338,000)	$ (3,426,000)	$ (6,107,000)
Reclassification to/(from) non-credit discount from/(to) the allowance for changes in payment timing expectations	0	(4,224,000)	310,000	(2,999,000)
Increase in allowance for expected credit losses for loan acquisitions during the period	0	(219,000)	0	(252,000)
Credit loss expense on mortgage loans	(10,000)	(70,000)	(53,000)	(114,000)
Net change in the allowance for credit losses	0	2,866,000	(1,112,000)	3,487,000
Reversal of allowance upon reclass of mortgage loans held-for-sale, net	413,000	0	4,281,000	0
Allowance for expected credit losses, end of period	$ 0	$ (5,985,000)	$ 0	$ (5,985,000)