CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $) In Thousands, except Share data	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Distributions in Excess of Net Income [Member]	Noncontrolling Interest [Member]
Balance at Dec. 31, 2009	$ (474,747)	$ 26	$ 543	$ 579,983	$ (24,443)	$ (884,666)	$ (146,190)
Balance, shares (in shares) at Dec. 31, 2009		33,839,235	54,321,586
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock pursuant to Continuing Offer (Notes 5, 7, and 8)			1	(1)
Issuance of stock pursuant to Continuing Offer, shares (in shares)		(126,109)	126,116
Share based compensation under employee and director benefit plans (Note 7)	6,312		3	6,309
Share Based Compensation Under Employee And Director Benefit Plans Shares			231,843
Adjustments of noncontrolling interest (Note 5)	(623)			(623)	34		589
Purchase of additional interest in subsidiary	623
Dividend equivalents (Note 7)	(94)					(94)
Dividends and distributions	(83,757)					(53,344)	(30,413)
Net income	35,297					21,776	13,521
Unrealized gain (loss) on interest rate instruments and other	5,899				2,330		3,569
Reclassification adjustment for amounts recognized in net income	631				425		206
Balance at Jun. 30, 2010	(510,459)	26	547	585,668	(21,654)	(916,328)	(158,718)
Balance, shares (in shares) at Jun. 30, 2010		33,713,126	54,679,545
Balance at Dec. 31, 2010	(527,911)	26	547	589,881	(14,925)	(939,290)	(164,150)
Balance, shares (in shares) at Dec. 31, 2010		33,713,126	54,696,054
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, New Issues	111,926		20	111,906
Stock Issued During Period, Shares, New Issues	2,012,500		2,012,500
Issuance of stock pursuant to Continuing Offer (Notes 5, 7, and 8)		(1)	11	(10)
Issuance of stock pursuant to Continuing Offer, shares (in shares)		(1,092,690)	1,092,766
Share based compensation under employee and director benefit plans (Note 7)	3,384		1	3,383
Share Based Compensation Under Employee And Director Benefit Plans Shares			88,210
Adjustments of noncontrolling interest (Note 5)	(40,762)			(40,762)	490		40,272
Purchase of additional interest in subsidiary	40,762
Contributions from Noncontrolling Interests (excludes $62 contribution from redeemable noncontrolling interests) (Note 5)	31,417						31,417
Dividend equivalents (Note 7)	(53)					(53)
Dividends and distributions	(91,009)					(57,013)	(33,996)
Net income	44,734
Net income (excludes $292 of net loss attributable to redeemable noncontrolling interests) (Note 5)	45,026					27,139	17,887
Unrealized gain (loss) on interest rate instruments and other	(337)				(291)		(46)
Reclassification adjustment for amounts recognized in net income	725				503		222
Balance at Jun. 30, 2011	$ (426,832)	$ 25	$ 579	$ 664,398	$ (14,223)	$ (969,217)	$ (108,394)
Balance, shares (in shares) at Jun. 30, 2011		32,620,436	57,889,530