CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Total Stockholders’ Equity	Preferred Stock	Common Stock	Additional Paid-in Capital	Cumulative Distributions in Excess of Net Income	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Balance (in shares) at Dec. 31, 2016			5,750,000	65,285,614
Balance at Dec. 31, 2016	$ 1,015,609	$ 1,015,574	$ 58	$ 653	$ 1,208,862	$ (192,201)	$ (1,798)	$ 35
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	18,791	18,823				18,823		(32)
Other comprehensive income	170	170					170
Amortization of stock-based compensation	2,860	2,860			2,860
Common stock issuance, net (in shares)				125,054
Common stock issuance, net	(2,814)	(2,814)		$ 1	(2,815)
Preferred dividends	(2,561)	(2,561)				(2,561)
Common dividends	(27,702)	(27,702)				(27,702)
Balance (in shares) at Mar. 31, 2017			5,750,000	65,410,668
Balance at Mar. 31, 2017	1,004,353	1,004,350	$ 58	$ 654	1,208,907	(203,641)	(1,628)	3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of ASU 2017-12 adoption	0	0				(795)	795
Balance (in shares) at Dec. 31, 2017			5,750,000	178,255,843
Balance at Dec. 31, 2017	3,437,249	3,432,807	$ 58	$ 1,783	3,636,913	(217,236)	11,289	4,442
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	62,481	62,471				62,471		10
Other comprehensive income	8,729	8,729					8,729
Distributions to noncontrolling interests	(37)							(37)
Amortization of stock-based compensation	1,398	1,398			1,398
Common stock issuance, net (in shares)				26,527
Common stock issuance, net	(202)	(202)		$ 0	(202)
Preferred dividends	(2,561)	(2,561)				(2,561)
Common dividends	(80,491)	(80,491)				(80,491)
Balance (in shares) at Mar. 31, 2018			5,750,000	178,282,370
Balance at Mar. 31, 2018	$ 3,426,566	$ 3,422,151	$ 58	$ 1,783	$ 3,638,109	$ (238,612)	$ 20,813	$ 4,415