Equity - Additional Information (Detail) - USD ($)										3 Months Ended		9 Months Ended
	Jan. 10, 2017	Oct. 08, 2015	Aug. 06, 2015	Jul. 10, 2015	Jul. 09, 2015	May. 05, 2015	Apr. 09, 2015	Apr. 08, 2015	Jan. 08, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Class of Stock [Line Items]
Net proceeds after offering costs and commissions from sale of shares												$ 7,400,000
Authorized capital shares of common stock										500,000,000		500,000,000		500,000,000
Authorized capital shares of preferred stock										100,000,000		100,000,000		100,000,000
Shares of common stock issued										26,260,685		26,260,685		25,022,701
Shares of common stock outstanding										26,260,685		26,260,685		25,022,701
Preferred stock issued										0		0		0
Preferred stock outstanding										0		0		0
Percentage of Operating Partnership held										62.50%		62.50%		62.90%
Aggregate cash dividends and distributions, paid												$ 20,050,000	$ 15,729,000
Cash dividend per share, declared										$ 0.17	$ 0.16	$ 0.51	$ 0.48
Common Class A [Member]
Class of Stock [Line Items]
Common stock units not held by company										14,768,507		14,768,507
Columbus Village in Virginia Beach [Member] | Class B Units [Member]
Class of Stock [Line Items]
Acquisition, common stock issued				1,000,000
Columbus Village in Virginia Beach [Member] | Class C Units [Member]
Class of Stock [Line Items]
Acquisition, common stock issued				275,000
Columbus Village in Virginia Beach [Member] | Scenario, Forecast [Member] | Class C Units [Member]
Class of Stock [Line Items]
Acquisition, common stock issued	275,000
Common Stock [Member]
Class of Stock [Line Items]
Number of shares issued and sold												747,163
Numbers shares issued and sold, weighted average price per share										$ 10.29		$ 10.29
Shares of common stock outstanding										26,260,685		26,260,685		25,022,701
Maximum [Member] | Common Stock [Member]
Class of Stock [Line Items]
Proceeds from issuance of common stock						$ 50,000,000
Private Placement [Member] | Perry Hall Marketplace [Member]
Class of Stock [Line Items]
Acquisition, common stock issued								415,500
Common Stockholders [Member]
Class of Stock [Line Items]
Aggregate cash dividends and distributions, paid					$ 4,400,000		$ 4,300,000		$ 4,000,000
Common Stockholders [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Aggregate cash dividends and distributions, paid		$ 4,500,000
Class A Unit Holders [Member]
Class of Stock [Line Items]
Aggregate cash dividends and distributions, paid					$ 2,500,000		$ 2,500,000		$ 2,400,000
Class A Unit Holders [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Aggregate cash dividends and distributions, paid		$ 2,500,000
Dividend Declared [Member]
Class of Stock [Line Items]
Cash dividend per share, declared			$ 0.17
Cash dividend, date of record												Oct. 01, 2015