Net Operating Income of Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Rental revenues	$ 14,231	$ 13,609	$ 27,629	$ 26,996
Segment revenues	23,291	12,383	41,247	27,024
Other		(33)		(37)
Property expenses	(3,399)	(2,944)	(6,628)	(5,808)
Segment expenses	(22,503)	(11,501)	(39,961)	(25,493)
Net operating income	10,372	10,338	19,827	20,327
Office real estate
Segment Reporting Information [Line Items]
Rental revenues	6,420	6,566	12,906	12,959
Property expenses	(1,940)	(1,804)	(3,886)	(3,650)
Net operating income	4,480	4,762	9,020	9,309
Retail real estate
Segment Reporting Information [Line Items]
Rental revenues	5,383	5,187	10,388	10,287
Property expenses	(1,629)	(1,477)	(3,309)	(3,006)
Net operating income	3,754	3,710	7,079	7,281
Multifamily residential real estate
Segment Reporting Information [Line Items]
Rental revenues	2,428	1,856	4,335	3,750
Property expenses	(1,078)	(839)	(1,893)	(1,507)
Net operating income	1,350	1,017	2,442	2,243
General contracting and real estate services
Segment Reporting Information [Line Items]
Segment revenues	23,291	12,383	41,247	27,024
Segment expenses	(22,503)	(11,501)	(39,961)	(25,493)
Net operating income	$ 788	$ 882	$ 1,286	$ 1,531