Earnings per Share and Unit (Details) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended	3 Months Ended								12 Months Ended
	Feb. 09, 2012	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted Average Limited Partnership Units Outstanding, Basic										177,164,000	177,164,000	270,706,000
Numerator [Abstract]
Less: preferred unit distributions	$ 1,000
Net (loss) income attributable to common stockholders		(37,179)	11,637	5,697	13,181	8,139	8,510	12,861	2,185
(Loss) income per common share - basic (note 14):
Net income attributable to common stockholders (in dollars per share)		$ (0.41)	$ 0.13	$ 0.06	$ 0.14	$ 0.10	$ 0.09	$ 0.14	$ 0.02
(Loss) income per common share - diluted (note 14):
Net income (loss) attributable to common stockholders (in dollars per share)		$ (0.41)	$ 0.13	$ 0.06	$ 0.14	$ 0.10	$ 0.09	$ 0.14	$ 0.02
Parent Company [Member]
Numerator [Abstract]
Income from continuing operations										505	45,344	3,106
Income from discontinued operations										23,546	8,040	8,902
Gain on sale of real estate										2,158	2,404	993
Net income										26,209	55,788	13,001
Less: preferred stock dividends										32,531	19,675	19,675
Net income attributable to noncontrolling interests										342	4,418	4,185
Net (loss) income attributable to common stockholders										(6,664)	31,695	(10,859)
Less: dividends paid on unvested restricted stock										572	615	542
Net income attributable to common stockholders - basic										(7,236)	31,080	(11,401)
Add: dividends paid on Treasury Method restricted stock										0	18	0
Net (loss) income for common stockholders - diluted										(7,236)	31,098	(11,401)
Denominator [Abstract]
Weighted average common shares/units outstanding for basic EPS/EPU										89,630,000	87,825,000	81,068,000
Incremental shares to be issued under unvested restricted stock										39,000	0	0
Incremental shares under Forward Equity Offering										0	424,000	1,534,000
Weighted average common shares/units outstanding for diluted EPS/EPU										89,669,000	88,249,000	82,602,000
(Loss) income per common share - basic (note 14):
Continuing operations (in dollars per share)										(0.34)	0.26	(0.25)
Discontinued operations (in dollars per share)										0.26	0.09	0.11
Net income attributable to common stockholders (in dollars per share)										(0.08)	0.35	(0.14)
(Loss) income per common share - diluted (note 14):
Continuing operations (in dollars per share)										(0.34)	0.26	(0.25)
Discontinued operations (in dollars per share)										0.26	0.09	0.11
Net income (loss) attributable to common stockholders (in dollars per share)										(0.08)	0.35	(0.14)
Partnership Interest [Member]
Numerator [Abstract]
Income from continuing operations										505	45,344	3,106
Income from discontinued operations										23,546	8,040	8,902
Gain on sale of real estate										2,158	2,404	993
Net income										26,209	55,788	13,001
Less: preferred unit distributions										31,902	23,400	23,400
Preferred unit distributions										23,658	23,400	23,400
Net income attributable to noncontrolling interests										865	590	376
Net (loss) income attributable to common unit holders										(6,558)	31,798	(10,775)
Less: dividends paid on unvested restricted stock										572	615	542
Net income attributable to common stockholders - basic										(7,130)	31,183	(11,317)
Add: dividends paid on Treasury Method restricted stock										0	18	0
Net (loss) income for common stockholders - diluted										(7,130)	31,201	(11,317)
Denominator [Abstract]
Weighted average common shares/units outstanding for basic EPS/EPU										89,808,000	88,002,000	81,339,000
Incremental shares to be issued under unvested restricted stock										39,000	0	0
Incremental shares under Forward Equity Offering										0	424,000	1,534,000
Weighted average common shares/units outstanding for diluted EPS/EPU										89,847,000	88,426,000	82,873,000
Earnings Per Common Unit, Basic [Abstract]
Continuing operations (in dollars per share)										(0.34)	0.26	(0.25)
Discontinued operations (in dollars per share)										0.26	0.09	0.11
Net income attributable to common unit holders (in dollars per share)										(0.08)	0.35	(0.14)
Earnings Per Common Unit - Diluted [Abstract]
Continuing operations (in dollars per share)										(0.34)	0.26	(0.25)
Discontinued operations (in dollars per share)										0.26	0.09	0.11
Net (loss) income attributable to common unit holders										(0.08)	0.35	(0.14)