Condensed Consolidated Statements of Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Treasury Stock	Distributions in Excess of Net Income	Stockholders' Investment	Nonredeemable Noncontrolling Interests
Beginning Balance at Dec. 31, 2010	$ 792,851	$ 169,602	$ 106,962	$ 684,551	$ (86,840)	$ (114,196)	$ 760,079	$ 32,772
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	663					(2,695)	(2,695)	3,358
Common stock issued pursuant to:
Director stock grants	707		82	625			707
Stock option exercises	34		4	30	0	0	34	0
Restricted stock grants, net of amounts withheld for income taxes	(19)		244	(263)			(19)
Amortization of stock options and restricted stock, net of forfeitures	1,683		(8)	1,691			1,683
Change in fair value of redeemable noncontrolling interests	(526)			(526)			(526)
Contributions from noncontrolling interests	1,300							1,300
Distributions to noncontrolling interests	(1,712)							(1,712)
Cash preferred dividends paid	(9,680)					(9,680)	(9,680)
Cash common dividends paid	(13,982)					(13,982)	(13,982)
Ending Balance at Sep. 30, 2011	771,319	169,602	107,284	686,108	(86,840)	(140,553)	735,601	35,718
Beginning Balance at Dec. 31, 2011	637,395	169,602	107,272	687,835	(86,840)	(274,177)	603,692	33,703
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	14,156					12,413	12,413	1,743
Common stock issued pursuant to:
Director stock grants	540		72	468			540
Restricted stock grants, net of amounts withheld for income taxes	(169)		448	(617)			(169)
Amortization of stock options and restricted stock, net of forfeitures	1,422		(86)	1,508			1,422
Change in fair value of redeemable noncontrolling interests	0
Distributions to noncontrolling interests	(1,700)							(1,700)
Cash preferred dividends paid	(9,680)					(9,680)	(9,680)
Cash common dividends paid	(14,064)					(14,064)	(14,064)
Ending Balance at Sep. 30, 2012	$ 627,900	$ 169,602	$ 107,706	$ 689,194	$ (86,840)	$ (285,508)	$ 594,154	$ 33,746