Equity - Additional Information (Detail) - USD ($)								3 Months Ended		6 Months Ended
	Jul. 10, 2015	Jul. 09, 2015	May. 08, 2015	May. 05, 2015	Apr. 09, 2015	Apr. 08, 2015	Jan. 08, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Class of Stock [Line Items]
Net proceeds after offering costs and commissions from sale of shares										$ 3,400,000
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								25,855,220		25,855,220		25,022,701
Shares of common stock outstanding								25,855,220		25,855,220		25,022,701
Preferred stock issued								0		0		0
Preferred stock outstanding								0		0		0
Percentage of Operating Partnership held								63.70%		63.70%		62.90%
Aggregate cash dividends and distributions, paid										$ 13,144,000	$ 10,441,000
Cash dividend per share, declared								$ 0.17	$ 0.16	$ 0.34	$ 0.32
Scenario, Forecast [Member] | Common Class C [Member]
Class of Stock [Line Items]
Acquisition, common stock issued										275,000
Subsequent Event [Member] | Common Class B [Member]
Class of Stock [Line Items]
Acquisition, common stock issued	1,000,000
Common Stock [Member]
Class of Stock [Line Items]
Number of shares issued and sold										342,658
Numbers shares issued and sold, weighted average price per share								$ 10.49		$ 10.49
Shares of common stock outstanding								25,855,220		25,855,220		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					$ 4,300,000		$ 4,000,000
Common Stockholders [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Aggregate cash dividends and distributions, paid		$ 4,400,000
Common Unit Holders [Member]
Class of Stock [Line Items]
Aggregate cash dividends and distributions, paid					$ 2,500,000		$ 2,400,000
Common 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										Jul. 01, 2015