Identifiable net assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Assets	$ 709,166	$ 701,084	$ 678,190
Investments available for sale	0	0	4,317
Cash	158,415	178,294	162,273
Industrial Commercial [Member]
Segment Reporting Information [Line Items]
Assets	38,784	26,053	23,897
Asset Management [Member]
Segment Reporting Information [Line Items]
Assets	48,072	48,494	37,627
Development [Member]
Segment Reporting Information [Line Items]
Assets	212,384	188,834	176,386
Multifamily Segment [Member]
Segment Reporting Information [Line Items]
Assets	249,750	257,535	266,429
Unallocated Corporate Assets [Member]
Segment Reporting Information [Line Items]
Assets	$ 1,761	$ 1,874	$ 7,261