Earnings per Share and Unit (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	0 Months Ended	3 Months Ended
	Feb. 09, 2012	Mar. 31, 2012	Mar. 31, 2011
Income per common share/unit - diluted:
Weighted Average Limited Partnership Units Outstanding, Basic		177,164	177,164
Parent Company [Member]
Earnings Per Share [Abstract]
Income from continuing operations		$ 20,324	$ 7,011
Discontinued operations		6,411	1,119
Net income		26,735	8,130
Less: Preferred stock dividends		13,937	4,919
Less: Noncontrolling interests		(383)	1,026
Net income attributable to common stockholders		13,181	2,185
Less: Dividends paid on unvested restricted stock		231	240
Net income attributable to common stock/unit holders - basic		12,950	1,945
Add: Dividends paid on Treasury Method restricted stock		14	15
Net income for common stock unit/holders - diluted		12,964	1,960
Weighted average common shares/units outstanding for basic EPS/EPU		89,497	83,099
Incremental shares under Forward Equity Offering		0	1,695
Weighted average common shares/units outstanding for diluted EPS/EPU		89,497	84,794
Income per common share/unit - basic:
Continuing operations (in dollars per share)		$ 0.07	$ 0.01
Discontinued operations (in dollars per share)		$ 0.07	$ 0.01
Net income attributable to common stockholders (in dollars per share)		$ 0.14	$ 0.02
Income per common share/unit - diluted:
Continuing operations (in dollars per share)		$ 0.07	$ 0.01
Discontinued operations (in dollars per share)		$ 0.07	$ 0.01
Net income attributable to common stockholders (in dollars per share)		$ 0.14	$ 0.02
Earnings Per Unit [Abstract]
Income from continuing operations		20,324	7,011
Discontinued operations		6,411	1,119
Net income		26,735	8,130
Less: Noncontrolling interests		(383)	1,026
Less: Dividends paid on unvested restricted units		231	240
Add: Dividends paid on Treasury Method restricted units		14	15
Incremental units under Forward Equity Offering		0	1,695
Partnership Interest [Member]
Earnings Per Share [Abstract]
Income from continuing operations		20,324	7,011
Discontinued operations		6,411	1,119
Net income		26,735	8,130
Less: Noncontrolling interests		192	82
Less: Dividends paid on unvested restricted stock		231	240
Net income attributable to common stock/unit holders - basic		13,004	1,958
Add: Dividends paid on Treasury Method restricted stock		14	15
Net income for common stock unit/holders - diluted		13,018	1,973
Weighted average common shares/units outstanding for basic EPS/EPU		89,674	83,630
Incremental shares under Forward Equity Offering		0	1,695
Weighted average common shares/units outstanding for diluted EPS/EPU		89,674	85,325
Earnings Per Unit [Abstract]
Income from continuing operations		20,324	7,011
Discontinued operations		6,411	1,119
Net income		26,735	8,130
Preferred unit distributions	1,000	13,308	5,850
Less: Noncontrolling interests		192	82
Net income attributable to common unit holders		13,235	2,198
Less: Dividends paid on unvested restricted units		231	240
Add: Dividends paid on Treasury Method restricted units		$ 14	$ 15
Incremental units under Forward Equity Offering		0	1,695
Income per common unit - basic
Continuing operations (in dollars per share)		0.07	0.01
Discontinued operations (in dollars per share)		0.07	0.01
Net income attributable to common unit holders (in dollars per share)		0.14	0.02
Income per common unit - diluted
Continuing operations (in dollars per share)		0.07	0.01
Discontinued operations (in dollars per share)		0.07	0.01
Net income attributable to common unit holders (in dollars per share)		0.14	0.02