Equity - Additional Information (Details) - USD ($)										1 Months Ended	3 Months Ended		5 Months Ended	9 Months Ended
	Oct. 14, 2016	Oct. 13, 2016	Oct. 06, 2016	Aug. 04, 2016	Jul. 07, 2016	May 04, 2016	Apr. 07, 2016	Jan. 07, 2016	Jul. 10, 2015	May 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Class of Stock
Authorized capital shares of common stock (in shares)											500,000,000		500,000,000	500,000,000		500,000,000
Authorized capital shares of preferred stock (in shares)											100,000,000		100,000,000	100,000,000		100,000,000
Common stock, shares issued (in shares)											34,255,874		34,255,874	34,255,874		30,076,359
Common stock, shares outstanding (in shares)											34,255,874		34,255,874	34,255,874		30,076,359
Preferred stock issued (in shares)											0		0	0		0
Preferred stock outstanding (in shares)											0		0	0		0
Percentage of Operating Partnership held											66.20%		66.20%	66.20%		65.60%
Ownership interest percentage in properties											100.00%		100.00%	100.00%
Aggregate cash dividends and distributions, paid														$ 24,702,000	$ 20,050,000
Cash dividend per share, declared (in dollars per share)											$ 0.18	$ 0.17		$ 0.54	$ 0.51
Subsequent Event
Class of Stock
Acquisition, common units/shares issued or to be issued (in shares)		2,000,000
Acquisition, contract price		$ 26,200,000
Dividend Declared
Class of Stock
Cash dividend per share, declared (in dollars per share)				$ 0.18
Class A units
Class of Stock
Class A Units not held by Company (in shares)											16,518,474		16,518,474	16,518,474
Ownership interest percentage in properties											0.00%		0.00%	0.00%		0.00%
Operating Partnership | Class A units
Class of Stock
Aggregate cash dividends and distributions, paid					$ 2,900,000		$ 2,700,000	$ 2,500,000
Operating Partnership | Class A units | Subsequent Event
Class of Stock
Aggregate cash dividends and distributions, paid			$ 3,000,000
Operating Partnership | Class B units | Columbus Village
Class of Stock
Acquisition, common units/shares issued or to be issued (in shares)									1,000,000
Operating Partnership | Class C units | Columbus Village
Class of Stock
Acquisition, common units/shares issued or to be issued (in shares)									275,000
Common Stock
Class of Stock
Shares issued through public offering (in shares)														4,079,482
Common stock, shares outstanding (in shares)											34,255,874		34,255,874	34,255,874		30,076,359
Aggregate cash dividends and distributions, paid					$ 5,900,000		$ 5,600,000	$ 5,100,000
Common Stock | Subsequent Event
Class of Stock
Aggregate cash dividends and distributions, paid			$ 6,200,000
New ATM Program | Common Stock
Class of Stock
Maximum aggregate offering price of shares to be sold (up to)						$ 75,000,000.0
Shares issued through public offering (in shares)													2,926,563
Numbers shares issued and sold, weighted average price per share (in dollars per share)											$ 13.17		$ 13.17	$ 13.17
Net proceeds after offering costs and commissions from sale of shares													$ 37,700,000
New ATM Program | Common Stock | Subsequent Event
Class of Stock
Shares issued through public offering (in shares)	169,548
Numbers shares issued and sold, weighted average price per share (in dollars per share)	$ 13.11
Net proceeds after offering costs and commissions from sale of shares	$ 2,200,000
Prior ATM Program | Common Stock
Class of Stock
Maximum aggregate offering price of shares to be sold (up to)										$ 50,000,000.0
Shares issued through public offering (in shares)														1,152,919
Numbers shares issued and sold, weighted average price per share (in dollars per share)											$ 10.87		$ 10.87	$ 10.87
Net proceeds after offering costs and commissions from sale of shares														$ 12,200,000