Consolidated Statements of Changes In Equity - 3 months ended Mar. 31, 2017 - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	6.75% Series C Cumulative Redeemable Perpetual Preferred Stock	Distributions in Excess of Accumulated Earnings	Non- controlling interests – Common OP Units	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2016	$ 1,081,847	$ 854	$ 1,103,048	$ 136,144	$ (231,276)	$ 73,304	$ (227)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Common OP Units to Common Stock		12	15,339			(15,351)
Issuance of Common Stock through employee stock purchase plan	403		403
Compensation expenses related to restricted stock	1,755		1,755
Adjustment for Common OP Unitholders in the Operating Partnership	0		(2,885)			2,885
Adjustment for fair market value of swap	226						226
Net income	63,075			2,297	56,888	3,890
Distributions	(47,527)			(2,297)	(42,335)	(2,895)
Other	(33)		(32)		(1)
Balance at Mar. 31, 2017	$ 1,099,746	$ 866	$ 1,117,628	$ 136,144	$ (216,724)	$ 61,833	$ (1)