Note 12 - Segment Reporting - Income From Operations by Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Rental revenues									$ 100,873	$ 95,581	$ 85,723
Tenant recoveries									4,884	5,102	4,061
Garage and other income									4,240	3,269	3,221
Total revenues	$ 27,881	$ 27,948	$ 27,300	$ 26,868	$ 27,323	$ 26,008	$ 25,358	$ 25,263	109,997	103,952	93,005
Property operating expenses									27,267	27,029	25,442
Real estate taxes and insurance									22,293	20,685	17,740
General and administrative									9,873	9,944	8,405
Acquisition and organization costs									101	69	326
Depreciation and amortization									18,005	16,721	15,295
Total operating expenses									77,539	74,448	67,208
Income from operations									32,458	29,504	25,797
Total Assets	1,101,008				1,052,085				1,101,008	1,052,085	905,208
Interest expense									32,781	35,505	38,136
Capital expenditures									45,642	22,725	18,162
Commercial Segment [Member]
Rental revenues									21,508	21,914	18,558
Tenant recoveries									4,884	5,102	4,061
Garage and other income									933	875	1,587
Total revenues									27,325	27,891	24,206
Property operating expenses									4,312	4,328	4,113
Real estate taxes and insurance									4,687	4,438	4,024
General and administrative									1,078	801	748
Acquisition and organization costs
Depreciation and amortization									3,642	3,277	2,688
Total operating expenses									13,719	12,844	11,573
Income from operations									13,606	15,047	12,633
Total Assets	245,940				222,288				245,940	222,288	225,608
Interest expense									6,987	7,569	7,421
Capital expenditures									2,460	4,187	2,653
Residential Segment [Member]
Rental revenues									79,365	73,667	67,165
Tenant recoveries
Garage and other income									3,307	2,394	1,634
Total revenues									82,672	76,061	68,799
Property operating expenses									22,955	22,701	21,329
Real estate taxes and insurance									17,606	16,247	13,716
General and administrative									8,795	9,143	7,657
Acquisition and organization costs									101	69	326
Depreciation and amortization									14,363	13,444	12,607
Total operating expenses									63,820	61,604	55,635
Income from operations									18,852	14,457	13,164
Total Assets	$ 855,068				$ 829,797				855,068	829,797	679,600
Interest expense									25,794	27,936	30,715
Capital expenditures									$ 43,182	$ 18,538	$ 15,509