Segments - Net Income of Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information
Rental revenues	$ 49,560	$ 39,636	$ 142,679	$ 121,840
Rental expenses	12,717	10,223	34,841	27,907
Real estate taxes	5,543	4,760	16,314	13,326
Segment revenues	17,502	58,617	71,473	163,283
Gross profit	32,858	26,761	94,647	86,489
General contracting and real estate services
Segment Reporting Information
Segment revenues	17,502	58,617	71,473	163,283
Segment expenses	15,944	56,509	68,350	157,401
Gross profit	1,558	2,108	3,123	5,882
Office real estate
Segment Reporting Information
Rental revenues	11,933	11,456	35,324	32,142
Rental expenses	3,409	3,042	9,222	7,879
Real estate taxes	1,547	1,375	4,318	3,749
Gross profit	6,977	7,039	21,784	20,514
Retail real estate
Segment Reporting Information
Rental revenues	20,223	15,669	57,682	54,794
Rental expenses	3,270	2,618	9,119	8,096
Real estate taxes	2,100	1,808	6,307	5,981
Gross profit	14,853	11,243	42,256	40,717
Multifamily residential real estate
Segment Reporting Information
Rental revenues	17,404	12,511	49,673	34,904
Rental expenses	6,038	4,563	16,500	11,932
Real estate taxes	1,896	1,577	5,689	3,596
Gross profit	$ 9,470	$ 6,371	$ 27,484	$ 19,376