Consolidated Statements of Operations (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Rental and related revenue	$ 834,369,000	$ 742,883,000	$ 669,543,000
General contractor and service fee revenue	275,071,000	521,796,000	515,361,000
Revenues, Total	1,109,440,000	1,264,679,000	1,184,904,000
Expenses:
Rental expenses	153,135,000	144,617,000	134,866,000
Real estate taxes	113,643,000	102,277,000	88,606,000
General contractor and other services expenses	254,870,000	480,480,000	486,865,000
Depreciation and amortization	375,965,000	326,226,000	276,045,000
Costs and expenses, total	897,613,000	1,053,600,000	986,382,000
Operating Expenses [Abstract]
Equity in earnings of unconsolidated companies	4,674,000	4,565,000	7,980,000
Gain on sale of properties	344,000	68,549,000	39,662,000
Undeveloped land carrying costs	(8,829,000)	(8,934,000)	(9,203,000)
Impairment charges	0	(12,931,000)	(9,834,000)
Other operating expenses	(633,000)	(1,237,000)	(1,231,000)
General and administrative expenses	(46,424,000)	(43,107,000)	(41,329,000)
Other Cost and Expense, Operating	(50,868,000)	6,905,000	(13,955,000)
Operating income (loss)	160,959,000	217,984,000	184,567,000
Other Nonoperating Income (Expense) [Abstract]
Interest and other income, net	514,000	658,000	534,000
Interest expense	(245,170,000)	(220,455,000)	(186,407,000)
Gains (Losses) on Extinguishment of Debt	0	0	(16,349,000)
Acquisition-related activity	(4,192,000)	(1,188,000)	55,820,000
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(87,889,000)	(3,001,000)	38,165,000
Income Tax Expense (Benefit)	103,000	194,000	1,126,000
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	(87,786,000)	(2,807,000)	39,291,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent [Abstract]
Loss before gain on sales	(1,549,000)	(1,766,000)	(7,083,000)
Gain on sale of depreciable properties	13,467,000	100,882,000	33,054,000
Income (loss) from discontinued operations	11,918,000	99,116,000	25,971,000
Net income (loss)	(75,868,000)	96,309,000	65,262,000
Redeemable Preferred Stock Dividends	(46,438,000)	(60,353,000)	(69,468,000)
Other Preferred Stock Dividends and Adjustments	(5,730,000)	(3,796,000)	(10,438,000)
Net Income (Loss) Attributable to Noncontrolling Interest, Joint Venture Partners	382,000	(115,000)	(185,000)
Net Income (Loss) Attributable to Noncontrolling Interest	1,891,000	(744,000)	536,000
Net income (loss) attributable to common shareholders	(126,145,000)	31,416,000	(14,108,000)
Earnings Per Share, Basic [Abstract]
Continuing operations attributable to common shareholders	$ (0.53)	$ (0.27)	$ (0.18)
Discontinued operations attributable to common shareholders	$ 0.05	$ 0.38	$ 0.11
Total	$ (0.48)	$ 0.11	$ (0.07)
Earnings Per Share, Diluted [Abstract]
Continuing operations attributable to common shareholders	$ (0.53)	$ (0.27)	$ (0.18)
Discontinued operations attributable to common shareholders	$ 0.05	$ 0.38	$ 0.11
Total	$ (0.48)	$ 0.11	$ (0.07)
Weighted Average Number of Shares Outstanding, Basic	267,900	252,694	238,920
Weighted Average Number of Shares Outstanding, Diluted	267,900	259,598	238,920
Comprehensive Income (Loss) [Abstract]
Net income (loss)	(75,868,000)	96,309,000	65,262,000
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	1,704,000	2,419,000	4,198,000
Other Comprehensive Income (Loss), Net of Tax	1,704,000	2,419,000	4,198,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(74,164,000)	98,728,000	69,460,000
Subsidiary of Common Parent [Member]
Revenues:
Rental and related revenue	834,369,000	742,883,000	669,543,000
General contractor and service fee revenue	275,071,000	521,796,000	515,361,000
Revenues, Total	1,109,440,000	1,264,679,000	1,184,904,000
Expenses:
Rental expenses	153,135,000	144,617,000	134,866,000
Real estate taxes	113,643,000	102,277,000	88,606,000
General contractor and other services expenses	254,870,000	480,480,000	486,865,000
Depreciation and amortization	375,965,000	326,226,000	276,045,000
Costs and expenses, total	897,613,000	1,053,600,000	986,382,000
Operating Expenses [Abstract]
Equity in earnings of unconsolidated companies	4,674,000	4,565,000	7,980,000
Gain on sale of properties	344,000	68,549,000	39,662,000
Undeveloped land carrying costs	(8,829,000)	(8,934,000)	(9,203,000)
Impairment charges	0	(12,931,000)	(9,834,000)
Other operating expenses	(633,000)	(1,237,000)	(1,231,000)
General and administrative expenses	(46,424,000)	(43,107,000)	(41,329,000)
Other Cost and Expense, Operating	(50,868,000)	6,905,000	(13,955,000)
Operating income (loss)	160,959,000	217,984,000	184,567,000
Other Nonoperating Income (Expense) [Abstract]
Interest and other income, net	514,000	658,000	534,000
Interest expense	(245,170,000)	(220,455,000)	(186,407,000)
Gains (Losses) on Extinguishment of Debt	0	0	(16,349,000)
Acquisition-related activity	(4,192,000)	(1,188,000)	55,820,000
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(87,889,000)	(3,001,000)	38,165,000
Income Tax Expense (Benefit)	103,000	194,000	1,126,000
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	(87,786,000)	(2,807,000)	39,291,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent [Abstract]
Loss before gain on sales	(1,549,000)	(1,766,000)	(7,083,000)
Gain on sale of depreciable properties	13,467,000	100,882,000	33,054,000
Income (loss) from discontinued operations	11,918,000	99,116,000	25,971,000
Net income (loss)	(75,868,000)	96,309,000	65,262,000
Redeemable Preferred Stock Dividends	(46,438,000)	(60,353,000)	(69,468,000)
Other Preferred Stock Dividends and Adjustments	(5,730,000)	(3,796,000)	(10,438,000)
Net Income (Loss) Attributable to Noncontrolling Interest, Joint Venture Partners	382,000	(115,000)	(185,000)
Net income (loss) attributable to common shareholders	(128,418,000)	32,275,000	(14,459,000)
Earnings Per Share, Basic [Abstract]
Continuing operations attributable to common shareholders	$ (0.53)	$ (0.27)	$ (0.18)
Discontinued operations attributable to common shareholders	$ 0.05	$ 0.38	$ 0.11
Total	$ (0.48)	$ 0.11	$ (0.07)
Earnings Per Share, Diluted [Abstract]
Continuing operations attributable to common shareholders	$ (0.53)	$ (0.27)	$ (0.18)
Discontinued operations attributable to common shareholders	$ 0.05	$ 0.38	$ 0.11
Total	$ (0.48)	$ 0.11	$ (0.07)
Weighted Average Number of Shares Outstanding, Basic	272,729	259,598	244,870
Weighted Average Number of Shares Outstanding, Diluted	272,729	259,598	244,870
Comprehensive Income (Loss) [Abstract]
Net income (loss)	(75,868,000)	96,309,000	65,262,000
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	1,704,000	2,419,000	4,198,000
Other Comprehensive Income (Loss), Net of Tax	1,704,000	2,419,000	4,198,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ (74,164,000)	$ 98,728,000	$ 69,460,000