Condensed Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Total Stockholders' Equity [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Cumulative Distributions in Excess of Net Income [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]	Common Stock [Member]	Common Stock [Member] Total Stockholders' Equity [Member]	Common Stock [Member] Common Stock [Member]	Common Stock [Member] Additional Paid-in Capital [Member]
Beginning balance (in shares) at Dec. 31, 2015			5,750,000	65,182,335
Beginning balance at Dec. 31, 2015	$ 1,053,876	$ 1,053,770	$ 58	$ 652	$ 1,202,541	$ (142,148)	$ (7,333)	$ 106
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	21,723	21,764				21,764		(41)
Other comprehensive loss	(1,947)	(1,947)					(1,947)
Amortization of stock-based compensation	3,982	3,982			3,982
Common stock issuance, net (in shares)											105,981
Common stock issuance, net									$ (1,103)	$ (1,103)	$ 1	$ (1,104)
Preferred dividends	(5,121)	(5,121)				(5,121)
Common dividends	(54,498)	(54,498)				(54,498)
Ending balance (in shares) at Jun. 30, 2016			5,750,000	65,288,316
Ending balance at Jun. 30, 2016	1,016,912	1,016,847	$ 58	$ 653	1,205,419	(180,003)	(9,280)	65
Beginning balance (in shares) at Dec. 31, 2016			5,750,000	65,285,614
Beginning 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)	39,327	39,343				39,343		(16)
Other comprehensive loss	965	965					965
Amortization of stock-based compensation	4,848	4,848			4,848
Common stock issuance, net (in shares)											139,820
Common stock issuance, net									$ (2,814)	$ (2,814)	$ 1	$ (2,815)
Preferred dividends	(5,121)	(5,121)				(5,121)
Common dividends	(56,099)	(56,099)				(56,099)
Ending balance (in shares) at Jun. 30, 2017			5,750,000	65,425,434
Ending balance at Jun. 30, 2017	$ 996,715	$ 996,696	$ 58	$ 654	$ 1,210,895	$ (214,078)	$ (833)	$ 19