Segments - Net Operating Income of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Rental revenues	$ 21,303	$ 16,713	$ 59,401	$ 47,225
Segment revenues	53,822	31,532	129,959	71,261
Rental expenses	4,865	4,414	14,256	12,230
Real estate taxes	2,056	1,480	5,672	4,231
Net operating income	16,488	11,883	44,291	34,218
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net operating income	16,488	11,883	44,291	34,218
Operating Segments [Member] | Office Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	8,092	7,295	23,847	20,363
Rental expenses	1,758	1,742	5,216	4,756
Real estate taxes	734	609	2,228	1,697
Net operating income	5,600	4,944	16,403	13,910
Operating Segments [Member] | Retail Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	8,523	6,086	22,715	17,559
Rental expenses	1,478	1,255	4,223	3,764
Real estate taxes	810	540	2,080	1,546
Net operating income	6,235	4,291	16,412	12,249
Operating Segments [Member] | Multifamily Residential Real Estate [Member]
Segment Reporting Information [Line Items]
Rental revenues	4,688	3,332	12,839	9,303
Rental expenses	1,629	1,417	4,817	3,710
Real estate taxes	512	331	1,364	988
Net operating income	2,547	1,584	6,658	4,605
Operating Segments [Member] | General Contracting and Real Estate Services [Member]
Segment Reporting Information [Line Items]
Segment revenues	53,822	31,532	129,959	71,261
Segment expenses	51,716	30,468	125,141	67,807
Net operating income	$ 2,106	$ 1,064	$ 4,818	$ 3,454