Segments - Property Expenses 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 expenses	$ 3,840	$ 3,399	$ 7,816	$ 6,628
Real estate taxes	1,408	1,248	2,751	2,460
Property expenses	5,248	4,647	10,567	9,088
Office Real Estate [Member]
Segment Reporting Information [Line Items]
Rental expenses	1,427	1,400	3,014	2,805
Real estate taxes	544	540	1,088	1,081
Property expenses	1,971	1,940	4,102	3,886
Retail Real Estate [Member]
Segment Reporting Information [Line Items]
Rental expenses	1,187	1,143	2,509	2,363
Real estate taxes	503	486	1,006	946
Property expenses	1,690	1,629	3,515	3,309
Multifamily Residential Real Estate [Member]
Segment Reporting Information [Line Items]
Rental expenses	1,226	856	2,293	1,460
Real estate taxes	361	222	657	433
Property expenses	$ 1,587	$ 1,078	$ 2,950	$ 1,893