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, 2013		5,750,000	38,788,745
Beginning balance at Dec. 31, 2013	$ 460,164	$ 58	$ 388	$ 534,639	$ (74,921)	$ 0	$ 460,164	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	24,673				24,702		24,702	(29)
Amortization of stock-based compensation	7,092			7,092			7,092
Common stock issuance, net (in shares)										8,839,239
Common stock issuance, net									$ 230,201	$ 88	$ 230,113	$ 230,201
Preferred dividends	(7,682)				(7,682)		(7,682)
Common dividends	(50,727)				(50,727)		(50,727)
Ending balance (in shares) at Sep. 30, 2014		5,750,000	47,627,984
Ending balance at Sep. 30, 2014	663,721	$ 58	$ 476	771,844	(108,628)	0	663,750	(29)
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)