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, 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), Including Portion Attributable to Nonredeemable Noncontrolling Interest	(9,314)	0	0	0	0	(9,885)	(9,885)	571
Common stock issued pursuant to:
Restricted stock grants, net of amounts withheld for income taxes	(171)		441	(612)			(171)
Amortization of stock options and restricted stock, net of forfeitures	583		(3)	586			583
Distributions to noncontrolling interests	(528)							(528)
Cash preferred dividends paid	(3,227)					(3,227)	(3,227)
Cash common dividends paid	(4,687)					(4,687)	(4,687)
Ending Balance at Mar. 31, 2012	620,051	169,602	107,710	687,809	(86,840)	(291,976)	586,305	33,746
Beginning Balance at Dec. 31, 2012	642,953	169,602	107,660	690,024	(86,840)	(260,104)	620,342	22,611
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	56,874	0	0	0	0	56,397	56,397	477
Common stock issued pursuant to:
Restricted stock grants, net of amounts withheld for income taxes	(1,172)		30	(1,202)			(1,172)
Amortization of stock options and restricted stock, net of forfeitures	361		7	354			361
Distributions to noncontrolling interests	(461)							(461)
Cash preferred dividends paid	(3,227)					(3,227)	(3,227)
Cash common dividends paid	(4,689)					(4,689)	(4,689)
Ending Balance at Mar. 31, 2013	$ 690,639	$ 169,602	$ 107,697	$ 689,176	$ (86,840)	$ (211,623)	$ 668,012	$ 22,627