Condensed Consolidated Statements of Equity (unaudited) - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Cumulative Distributions in Excess of Net Income [Member]	Accumulated Other Comprehensive Loss [Member]	Total Stockholders' Equity [Member]	Noncontrolling Interest [Member]	Common Stock [Member]	Common Stock [Member] Common Stock [Member]	Common Stock [Member] Additional Paid-in Capital [Member]	Common Stock [Member] Total Stockholders' Equity [Member]
Beginning balance (in shares) at Dec. 31, 2014		5,750,000	59,047,001
Beginning balance at Dec. 31, 2014	$ 941,823	$ 58	$ 590	$ 1,053,601	$ (110,841)	$ (1,542)	$ 941,866	$ (43)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	54,299				54,346		54,346	(47)
Other comprehensive loss	(4,095)					(4,095)	(4,095)
Amortization of stock-based compensation	5,872			5,872			5,872
Common stock issuance, net (in shares)										6,087,055
Common stock issuance, net									$ 142,447	$ 61	$ 142,386	$ 142,447
Preferred dividends	(7,682)				(7,682)		(7,682)
Common dividends	(73,420)				(73,420)		(73,420)
Ending balance (in shares) at Sep. 30, 2015		5,750,000	65,134,056
Ending balance at Sep. 30, 2015	1,059,244	$ 58	$ 651	1,201,859	(137,597)	(5,637)	1,059,334	(90)
Beginning balance (in shares) at Dec. 31, 2015		5,750,000	65,182,335
Beginning balance at Dec. 31, 2015	1,053,876	$ 58	$ 652	1,202,541	(142,148)	(7,333)	1,053,770	106
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	47,035				47,101		47,101	(66)
Other comprehensive loss	(2,049)					(2,049)	(2,049)
Amortization of stock-based compensation	6,775			6,775			6,775
Common stock issuance, net (in shares)										108,731
Common stock issuance, net									$ (1,103)	$ 1	$ (1,104)	$ (1,103)
Repurchase of common stock (in shares)			(31,230)
Repurchase of common stock	(725)			(725)			(725)
Preferred dividends	(7,682)				(7,682)		(7,682)
Common dividends	(82,240)				(82,240)		(82,240)
Ending balance (in shares) at Sep. 30, 2016		5,750,000	65,259,836
Ending balance at Sep. 30, 2016	$ 1,013,887	$ 58	$ 653	$ 1,207,487	$ (184,969)	$ (9,382)	$ 1,013,847	$ 40