Net Operating Income of Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Rental revenues	$ 14,899	$ 13,318	$ 42,528	$ 40,314
Segment revenues	21,896	13,631	63,143	40,655
Other		(2)		(39)
Property expenses	3,840	3,637	10,468	9,445
Segment expenses	20,907	12,707	60,868	38,200
Net operating income	10,731	9,405	30,558	29,732
Office real estate
Segment Reporting Information [Line Items]
Rental revenues	6,364	6,194	19,270	19,153
Property expenses	2,081	2,271	5,967	5,921
Net operating income	4,283	3,923	13,303	13,232
Retail real estate
Segment Reporting Information [Line Items]
Rental revenues	5,683	5,297	16,071	15,584
Property expenses	1,745	1,618	5,054	4,624
Net operating income	3,938	3,679	11,017	10,960
Multifamily residential real estate
Segment Reporting Information [Line Items]
Rental revenues	2,852	1,827	7,187	5,577
Property expenses	1,331	946	3,224	2,453
Net operating income	1,521	881	3,963	3,124
General contracting and real estate services
Segment Reporting Information [Line Items]
Segment revenues	21,896	13,631	63,143	40,655
Segment expenses	20,907	12,707	60,868	38,200
Net operating income	$ 989	$ 924	$ 2,275	$ 2,455