Consolidated Statements of Changes In Equity - 9 months ended Sep. 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			48			(48)
Issuance of Common Stock through exercise of options	5,232	2	5,230
Issuance of Common Stock through employee stock purchase plan	875		875
Issuance of Common Stock	50,000	7	49,993
Compensation expenses related to restricted stock	6,796		6,796
Repurchase of Common Stock or Common OP units	(274)		(274)
Adjustment for Common OP Unitholders in the Operating Partnership	0		(4,068)			4,068
Adjustment for fair market value of swap	(93)						(93)
Net income	144,751			6,910	127,071	10,770
Distributions	(124,540)			(6,910)	(108,444)	(9,186)
Other	(824)		(824)
Balance at Sep. 30, 2016	$ 1,074,614	$ 852	$ 1,096,916	$ 136,144	$ (231,879)	$ 73,227	$ (646)