CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Total Stockholders’ Equity	Preferred Stock	Common Stock	Additional Paid-in Capital	Cumulative Distributions in Excess of Earnings	Accumulated Other Comprehensive Income	Noncontrolling Interests	Common Stock	Common Stock Total Stockholders’ Equity	Common Stock Common Stock	Common Stock Additional Paid-in Capital	Preferred Stock	Preferred Stock Total Stockholders’ Equity	Preferred Stock Preferred Stock
Beginning Balance at Dec. 31, 2015	$ 693,744	$ 672,139	$ 0	$ 553	$ 722,722	$ (48,103)	$ (3,033)	$ 21,605
Beginning Balance, shares at Dec. 31, 2015				55,598,684
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, shares											10,350,000
Issuance of stock									$ 182,678	$ 182,678	$ 104	$ 182,574	$ 90,000	$ 90,000	$ 90,000
Offering costs	(11,771)	(11,771)	3,336		(8,435)
Share-based compensation, shares				77,093
Share-based compensation	2,990	1,490		$ 1	1,489			1,500
Shares acquired to satisfy employee tax withholding requirements on vesting restricted stock, shares				(25,236)
Shares acquired to satisfy employee tax withholding requirements on vesting restricted stock	(501)	(501)			(501)
Conversion of units to common stock, shares				47,800
Conversion of units to common stock		505			505			(505)
Acquisition of real estate portfolio	125							125
Net income	17,330	16,797				16,797		533
Other comprehensive loss	(2,794)	(2,731)					(2,731)	(63)
Common stock dividends	(25,345)	(25,345)				(25,345)
Distributions	(898)							(898)
Ending Balance at Sep. 30, 2016	945,558	923,261	86,664	$ 658	898,354	(56,651)	(5,764)	22,297
Ending Balance, shares at Sep. 30, 2016				66,048,341
Beginning Balance at Dec. 31, 2016	$ 962,140	939,315	86,651	$ 662	907,834	(59,277)	3,445	22,825
Beginning Balance, shares at Dec. 31, 2016	66,454,375			66,454,375
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, shares											11,043,880
Issuance of stock									$ 309,104	$ 309,104	$ 110	$ 308,994
Offering costs	$ (5,236)	(5,236)			(5,236)
Share-based compensation, shares				67,132
Share-based compensation	4,190	1,712		$ 1	1,711			2,478
Shares acquired to satisfy employee tax withholding requirements on vesting restricted stock, shares				(31,403)
Shares acquired to satisfy employee tax withholding requirements on vesting restricted stock	(798)	(798)			(798)
Conversion of units to common stock, shares				61,256
Conversion of units to common stock		618			618			(618)
Net income	27,585	26,901	3,966			22,935		684
Other comprehensive loss	418	425					425	(7)
Preferred stock dividends	(3,966)	(3,966)	(3,966)
Common stock dividends	(31,236)	(31,236)				(31,236)
Distributions	(998)							(998)
Ending Balance at Sep. 30, 2017	$ 1,261,203	$ 1,236,839	$ 86,651	$ 773	$ 1,213,123	$ (67,578)	$ 3,870	$ 24,364
Ending Balance, shares at Sep. 30, 2017	77,595,240			77,595,240