Consolidated Statements of Changes In Equity - 6 months ended Jun. 30, 2016 - 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, 2015	$ 992,691	$ 843	$ 1,039,140	$ 136,144	$ (250,506)	$ 67,623	$ (553)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Common OP Units to Common Stock			38			(38)
Issuance of Common Stock through exercise of options	5,232	2	5,230
Issuance of Common Stock through employee stock purchase plan	275		275
Issuance of Common Stock	50,000	7	49,993
Compensation expenses related to restricted stock	4,393		4,393
Repurchase of Common Stock or Common OP units	(274)		(274)
Adjustment for Common OP Unitholders in the Operating Partnership	0		(3,820)			3,820
Adjustment for fair market value of swap	(644)						(644)
Net income	97,995			4,614	86,073	7,308
Distributions	(82,929)			(4,614)	(72,190)	(6,125)
Other	(823)		(823)
Balance at Jun. 30, 2016	$ 1,065,916	$ 852	$ 1,094,152	$ 136,144	$ (236,623)	$ 72,588	$ (1,197)