Consolidated Statements Of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities:
Net income	$ 198,383	$ 203,083
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	330,003	245,608
Non-cash compensation expense	23,702	26,725
Income from unconsolidated joint ventures	(28,184)	(26,940)
Distributions of net cash flow from operations of unconsolidated joint ventures	27,222	9,189
Losses (gains) from investments in securities	481	(253)
Non-cash portion of interest expense	41,016	42,199
Settlement of accreted debt discount on repurchases of unsecured exchangeable senior notes		(13,230)
Losses from early extinguishments of debt		8,221
Suspension of development		(7,200)
Gain on sale of real estate		(2,734)
Change in assets and liabilities:
Cash held in escrows	(6,228)	(1,404)
Tenant and other receivables, net	13,097	2,922
Accrued rental income, net	(66,155)	(57,887)
Prepaid expenses and other assets	(66,597)	(24,107)
Accounts payable and accrued expenses	5,341	(30,720)
Accrued interest payable	27,228	8,631
Other liabilities	(15,664)	(19,998)
Tenant leasing costs	(40,786)	(29,251)
Total adjustments	244,476	129,771
Net cash provided by operating activities	442,859	332,854
Cash flows from investing activities:
Acquisitions of real estate	(41,100)	(103,785)
Construction in progress	(205,580)	(233,814)
Building and other capital improvements	(29,406)	(14,377)
Tenant improvements	(50,400)	(91,742)
Proceeds from land transaction	43,887
Proceeds from mortgage loan released from (placed in) escrow	267,500	(267,500)
Deposit on real estate released from (placed in) escrow	10,000	(10,000)
Acquisitions of note receivable		(22,500)
Issuance of note receivable	(6,375)
Capital contributions to unconsolidated joint ventures	(17,867)	(61,426)
Capital distributions from unconsolidated joint ventures		27,150
Investments in securities, net	(1,061)	2,288
Net cash used in investing activities	(30,402)	(775,706)
Cash flows from financing activities:
Proceeds from mortgage notes payable	1,178,306	268,964
Repayments of mortgage notes payable	(1,196,074)	(301,531)
Proceeds from unsecured senior notes		699,237
Repurchases of unsecured exchangeable senior notes		(172,294)
Deposit on mortgage loan financing
Deferred financing costs	(9,103)	(7,563)
Net proceeds from ATM stock issuances	439,037
Net proceeds from equity transactions	9,554	21,933
Dividends and distributions	(248,601)	(243,253)
Distributions to noncontrolling interest in property partnership	(1,500)	(1,500)
Net cash provided by financing activities	171,619	263,993
Net increase in cash and cash equivalents	584,076	(178,859)
Cash and cash equivalents, beginning of period	478,948	1,448,933
Cash and cash equivalents, end of period	1,063,024	1,270,074
Supplemental disclosures:
Cash paid for interest	258,121	274,699
Interest capitalized	36,201	26,412
Non-cash investing and financing activities:
Additions to real estate included in accounts payable	15,161	6,927
Mortgage note payable assumed in connection with the acquisition of real estate	143,900	202,604
Note receivable converted to real estate		22,500
Dividends and distributions declared but not paid	83,584	81,068
Conversions of noncontrolling interests to stockholders' equity	71,181	13,748
Issuance of restricted securities to employees and directors	$ 25,087	$ 19,222