Consolidated Statements of Operations and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenues:
Rental and related revenue	$ 237,350	$ 209,879
General contractor and service fee revenue	55,820	47,404
Revenues, total	293,170	257,283
Expenses:
Rental expenses	50,267	38,861
Real estate taxes	32,467	29,040
General contractor and other services expenses	47,271	38,341
Depreciation and amortization	98,059	92,993
Costs and expenses, total	228,064	199,235
Other operating activities:
Equity in earnings (loss) of unconsolidated companies	2,321	49,378
Gain on sale of properties	15,853	168
Earnings from sales of land	152	0
Undeveloped land carrying costs	(2,124)	(2,198)
Other Operating Income (Expense), Net	(92)	(68)
General and administrative expenses	(14,694)	(13,145)
Other Operating Activities, Net	1,416	34,135
Operating income	66,522	92,183
Other income (expenses):
Interest and other income, net	351	153
Interest expense	(55,257)	(57,181)
Acquisition-related activity	(14)	643
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	11,602	35,798
Income Tax Expense (Benefit)	(2,674)	0
Income (loss) from continuing operations	8,928	35,798
Discontinued operations:
Income (loss) before gain on sales	(132)	(629)
Gain on sale of depreciable properties	16,775	8,954
Income (loss) from discontinued operations	16,643	8,325
Net income (loss)	25,571	44,123
Dividends on preferred shares/units	(7,037)	(9,550)
Adjustments for redemption of preferred shares/units	483	(5,932)
Net (income) loss attributable to noncontrolling interests	(334)	(598)
Net income (loss) attributable to common shareholders/unitholders	18,683	28,043
Basic net income (loss) per common share/unit:
Continuing operations attributable to common shareholders/unitholders	$ 0.01	$ 0.06
Discontinued operations attributable to common shareholders/unitholders	$ 0.05	$ 0.03
Total	$ 0.06	$ 0.09
Diluted net income (loss) per common share/unit:
Continuing operations attributable to common shareholders/unitholders	$ 0.01	$ 0.06
Discontinued operations attributable to common shareholders/unitholders	$ 0.05	$ 0.03
Total	$ 0.06	$ 0.09
Weighted average number of common shares/units outstanding	327,106	314,936
Weighted average number of common shares/units and potential dilutive securities	331,716	319,571
Comprehensive income (loss):
Net income (loss)	25,571	44,123
Other comprehensive income:
Amortization of interest contracts	(287)	457
Other	0	80
Total other comprehensive income	(287)	537
Comprehensive income (loss)	25,284	44,660
Subsidiary of Common Parent [Member]
Revenues:
Rental and related revenue	237,350	209,879
General contractor and service fee revenue	55,820	47,404
Revenues, total	293,170	257,283
Expenses:
Rental expenses	50,267	38,861
Real estate taxes	32,467	29,040
General contractor and other services expenses	47,271	38,341
Depreciation and amortization	98,059	92,993
Costs and expenses, total	228,064	199,235
Other operating activities:
Equity in earnings (loss) of unconsolidated companies	2,321	49,378
Gain on sale of properties	15,853	168
Earnings from sales of land	152	0
Undeveloped land carrying costs	(2,124)	(2,198)
Other Operating Income (Expense), Net	(92)	(68)
General and administrative expenses	(14,694)	(13,145)
Other Operating Activities, Net	1,416	34,135
Operating income	66,522	92,183
Other income (expenses):
Interest and other income, net	351	153
Interest expense	(55,257)	(57,181)
Acquisition-related activity	(14)	643
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	11,602	35,798
Income Tax Expense (Benefit)	(2,674)	0
Income (loss) from continuing operations	8,928	35,798
Discontinued operations:
Income (loss) before gain on sales	(132)	(629)
Gain on sale of depreciable properties	16,775	8,954
Income (loss) from discontinued operations	16,643	8,325
Net income (loss)	25,571	44,123
Dividends on preferred shares/units	(7,037)	(9,550)
Adjustments for redemption of preferred shares/units	483	(5,932)
Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, NonRedeemable	(84)	(206)
Net income (loss) attributable to common shareholders/unitholders	18,933	28,435
Basic net income (loss) per common share/unit:
Continuing operations attributable to common shareholders/unitholders	$ 0.01	$ 0.06
Discontinued operations attributable to common shareholders/unitholders	$ 0.05	$ 0.03
Total	$ 0.06	$ 0.09
Diluted net income (loss) per common share/unit:
Continuing operations attributable to common shareholders/unitholders	$ 0.01	$ 0.06
Discontinued operations attributable to common shareholders/unitholders	$ 0.05	$ 0.03
Total	$ 0.06	$ 0.09
Weighted average number of common shares/units outstanding	331,493	319,341
Weighted average number of common shares/units and potential dilutive securities	331,716	319,571
Comprehensive income (loss):
Net income (loss)	25,571	44,123
Other comprehensive income:
Amortization of interest contracts	(287)	457
Other	0	80
Total other comprehensive income	(287)	537
Comprehensive income (loss)	$ 25,284	$ 44,660