Segments - Net Operating Income of Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Rental revenues	$ 15,319	$ 14,231	$ 30,512	$ 27,629
Segment revenues	20,495	23,291	39,729	41,247
Property expenses	5,248	4,647	10,567	9,088
Segment expenses	19,354	22,503	37,339	39,961
Net operating income	11,212	10,372	22,335	19,827
Office Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	6,519	6,420	13,068	12,906
Property expenses	1,971	1,940	4,102	3,886
Net operating income	4,548	4,480	8,966	9,020
Retail Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	5,703	5,383	11,473	10,388
Property expenses	1,690	1,629	3,515	3,309
Net operating income	4,013	3,754	7,958	7,079
Multifamily Residential Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	3,097	2,428	5,971	4,335
Property expenses	1,587	1,078	2,950	1,893
Net operating income	1,510	1,350	3,021	2,442
General Contracting and Real Estate Services [Member]
Segment Reporting Information [Line Items]
Segment revenues	20,495	23,291	39,729	41,247
Segment expenses	19,354	22,503	37,339	39,961
Net operating income	$ 1,141	$ 788	$ 2,390	$ 1,286