CONSOLIDATED STATEMENTS OF EQUITY - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Total	Shares of Beneficial Interest, $1.00 Par [Member]	Capital Contributed In Excess Of Par [Member]	Accumulated Other Comprehensive Loss [Member]	Distributions in Excess of Net Income [Member]	Non-controlling interest [Member]	Series B [Member]	Series B [Member] Distributions in Excess of Net Income [Member]	Series A [Member]	Series A [Member] Distributions in Excess of Net Income [Member]	Series A Preferred Shares, $25 plus accrued dividends Liquidation Value [Member]	Series B Preferred Shares, $25 plus accrued dividends Liquidation Value [Member]
Shares Issued Upon Redemption Of Operating Partnership Units		$ 29	$ 577			$ (606)
December 31, 2014 at Dec. 31, 2014	$ 844,737	68,801	1,474,183	$ (6,002)	$ (721,605)	29,279					$ 46	$ 35
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(84,846)					(8,073)
Net Income (Loss), Excluding Portion Attributable to Noncontrolling Interest					(76,773)
Other comprehensive loss	(2,451)			(2,187)		(264)
Shares issued under employee compensation plans, net of shares retired	(4,574)	360	(4,934)
Amortization of deferred compensation	4,678		4,678
Distributions paid to common shareholders ($0.63 per share)	(43,556)				(43,556)
Distributions paid to preferred shareholders							$ (4,770)	$ (4,770)	$ (7,116)	$ (7,116)
Noncontrolling interests:
Distributions paid to Operating Partnership unit holders ($0.63 per unit)	(3,951)					(3,951)
September 30, 2015 at Sep. 30, 2015	843,318	$ 69,190	$ 1,474,504	$ (8,189)	$ (853,820)	$ 161,552					$ 46	$ 35
Noncontrolling interests:
Operating Partnership Units Issued As Consideration For Acquisition	$ 145,188