Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating Activities
Net income	$ 76,721	$ 99,931
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	143,933	117,060
Loss on early extinguishment of debt	2,225	6,485
Gain on sale of land parcel	(1,864)	(46)
Gain on sale of real estate	(1,564)
Non-cash impairment of real estate	9,799	994
Amortization of loan fees and costs	7,327	6,749
Amortization of debt premiums/discounts	401	3,254
Amortization of acquired above and below market leases	(2,356)	(8,520)
Deferred rent	(19,216)	(17,239)
Stock compensation expense	10,412	8,449
Equity in loss related to investments	26
Gain on sales of investments	(12,316)	(3,555)
Loss on sales of investments	1,607	1,240
Changes in operating assets and liabilities:
Restricted cash	441	489
Tenant receivables	(2,637)	(1,328)
Deferred leasing costs	(23,597)	(51,581)
Other assets	(3,230)	(8,735)
Accounts payable, accrued expenses, and tenant security deposits	41,378	26,325
Net cash provided by operating activities	227,490	179,972
Investing Activities
Proceeds from sale of property	36,179	17,339
Distributions from unconsolidated real estate entity related to sale of land parcel	22,250
Additions to properties	(406,066)	(293,688)
Purchase of properties	(42,171)	(307,839)
Change in restricted cash related to construction projects	(11,453)	(2,891)
Contributions to unconsolidated real estate entity	(5,042)	(3,256)
Additions to investments	(21,997)	(19,663)
Proceeds from investments	19,905	14,496
Net cash used in investing activities	(408,395)	(595,502)
Financing Activities
Borrowings from secured notes payable	2,874
Repayments of borrowings from secured notes payable	(8,125)	(30,181)
Proceeds from issuance of unsecured senior notes payable	544,649
Repurchase of unsecured senior convertible notes	(84,801)	(221,439)
Principal borrowings from unsecured senior line of credit and unsecured senior bank term loans	623,147	1,990,317
Repayments of borrowings from unsecured senior line of credit	(580,147)	(1,174,317)
Repayment of unsecured senior bank term loan	(250,000)	(500,000)
Redemption of Series C Preferred Stock	(129,638)
Proceeds from issuance of Series E Preferred Stock	124,868
Proceeds from issuance of common stock	98,443	451,539
Change in restricted cash related to financings	(10,476)	2,591
Deferred financing costs paid	(20,417)	(20,268)
Proceeds from exercise of stock options	155	1,165
Dividends paid on common stock	(92,743)	(77,787)
Dividends paid on preferred stock	(21,348)	(21,268)
Distributions to redeemable noncontrolling interests	(943)	(939)
Redemption of redeemable noncontrolling interests	(150)
Contributions by noncontrolling interests	1,626
Distributions to noncontrolling interests	(770)	(2,084)
Net cash provided by financing activities	196,204	397,329
Effect of exchange rate changes on cash and cash equivalents	1,066	25
Net increase (decrease) in cash and cash equivalents	16,365	(18,176)
Cash and cash equivalents at beginning of period	78,539	91,232
Cash and cash equivalents at end of period	94,904	73,056
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized	30,952	38,013
Non-Cash Investing Activities
Note receivable from sale of real estate	$ (6,125)