Segments - Net Operating Income of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Rental revenues	$ 19,908	$ 15,319	$ 38,098	$ 30,512
Segment revenues	47,066	20,495	76,137	39,729
Rental expenses	4,631	3,840	9,391	7,816
Segment expenses	45,283	19,354	73,425	37,339
Real estate taxes	1,959	1,408	3,616	2,751
Net operating income	15,101	11,212	27,803	22,335
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net operating income	15,101	11,212	27,803	22,335
Operating Segments [Member] | Office Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	8,052	6,519	15,755	13,068
Rental expenses	1,704	1,427	3,458	3,014
Real estate taxes	803	544	1,494	1,088
Net operating income	5,545	4,548	10,803	8,966
Operating Segments [Member] | Retail Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	7,567	5,703	14,192	11,473
Rental expenses	1,346	1,187	2,745	2,509
Real estate taxes	704	503	1,270	1,006
Net operating income	5,517	4,013	10,177	7,958
Operating Segments [Member] | Multifamily Residential Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	4,289	3,097	8,151	5,971
Rental expenses	1,581	1,226	3,188	2,293
Real estate taxes	452	361	852	657
Net operating income	2,256	1,510	4,111	3,021
Operating Segments [Member] | General Contracting and Real Estate Services [Member]
Segment Reporting Information [Line Items]
Segment revenues	47,066	20,495	76,137	39,729
Segment expenses	45,283	19,354	73,425	37,339
Net operating income	$ 1,783	$ 1,141	$ 2,712	$ 2,390