Consolidated Statements of Changes in Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit and Distributions	Total Stockholders' Equity	Non-controlling Interests Operating partnership	Non-controlling Interests Joint venture
Balance at beginning of year at Dec. 31, 2012	$ 473,537	$ 50	$ 462	$ 468,820	$ (528)	$ (31,985)	$ 436,819	$ 36,718
Balance (in shares) at Dec. 31, 2012		5,000,000	46,159,652
Changes in equity
Net proceeds from sale of common stock	300,166		345	299,821			300,166
Net proceeds from sale of common stock (in shares)			34,500,000
Net proceeds from sale of preferred stock	81,723	34		81,689			81,723
Net proceeds from sale of preferred stock (in shares)		3,400,000
Common stock redemption of common units			25	15,365			15,390	(15,390)
Common stock redemption of common units (in shares)			2,466,404
Contribution by non-controlling interests in joint venture	7,500								7,500
Dividends paid	(33,748)					(32,735)	(32,735)	(1,013)
Equity-based compensation	1,616		3	1,613			1,616
Equity-based compensation (in shares)			325,758
Other comprehensive (loss) income	(1,310)				(1,253)		(1,253)	(57)
Net income (loss)	7,973					7,757	7,757	(108)	324
Balance at end of period at Sep. 30, 2013	837,457	84	835	867,308	(1,781)	(56,963)	809,483	20,150	7,824
Balance (in shares) at Sep. 30, 2013		8,400,000	83,451,814
Balance at beginning of year at Dec. 31, 2013	822,378	84	854	882,858	(1,379)	(72,577)	809,840	4,722	7,816
Balance (in shares) at Dec. 31, 2013		8,400,000	85,402,408
Changes in equity
Common stock redemption of common units			2	581			583	(583)
Common stock redemption of common units (in shares)			198,292
Common units issued for acquisition	3,685							3,685
Acquisition of non-controlling interest in joint venture	(8,232)			(415)			(415)		(7,817)
Dividends paid	(42,187)					(41,822)	(41,822)	(365)
Equity-based compensation	2,843		3	2,806			2,809	34
Equity-based compensation (in shares)			319,590
Other comprehensive (loss) income	111				110		110	1
Net income (loss)	16,192					16,146	16,146	45	1
Balance at end of period at Sep. 30, 2014	$ 794,790	$ 84	$ 859	$ 885,830	$ (1,269)	$ (98,253)	$ 787,251	$ 7,539
Balance (in shares) at Sep. 30, 2014		8,400,000	85,920,290