Segments - Net Operating Income of Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]
Rental revenues	$ 16,713	$ 14,899	$ 47,225	$ 42,528
Segment revenues	31,532	21,896	71,261	63,143
Property expenses	5,894	5,157	16,461	14,245
Segment expenses	30,468	20,907	67,807	60,868
Net operating income	11,883	10,731	34,218	30,558
Office Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	7,295	6,364	20,363	19,270
Property expenses	2,351	2,081	6,453	5,967
Net operating income	4,944	4,283	13,910	13,303
Retail Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	6,086	5,683	17,559	16,071
Property expenses	1,795	1,745	5,310	5,054
Net operating income	4,291	3,938	12,249	11,017
Multifamily Residential Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	3,332	2,852	9,303	7,187
Property expenses	1,748	1,331	4,698	3,224
Net operating income	1,584	1,521	4,605	3,963
General Contracting and Real Estate Services [Member]
Segment Reporting Information [Line Items]
Segment revenues	31,532	21,896	71,261	63,143
Segment expenses	30,468	20,907	67,807	60,868
Net operating income	$ 1,064	$ 989	$ 3,454	$ 2,275