Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 78,671	$ 4,867
Adjustments to reconcile net income to net cash provided by operating activities (including discontinued operations):
Depreciation and amortization of building and improvements and leasing costs	36,464	29,059
Increase in provision for bad debts	2	26
Depreciation of furniture, fixtures and equipment	288	252
Noncash amortization of share-based compensation awards	1,287	1,106
Noncash amortization of deferred financing costs and debt discounts and premiums	2,976	3,450
Noncash amortization of net (below)/above market rents (Note 3)	(525)	653
Net gain on dispositions of discontinued operations (Note 14)	(72,809)	0
Noncash amortization of deferred revenue related to tenant-funded tenant improvements	(2,261)	(2,326)
Straight-line rents	(5,487)	(4,340)
Net change in other operating assets	(3,869)	(1,816)
Net change in other operating liabilities	14,956	12,866
Insurance proceeds received for property damage	(951)	0
Net cash provided by operating activities	48,742	43,797
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for acquisition of operating properties (Note 2)	(162,380)	(33,000)
Expenditures for operating properties	(17,307)	(15,985)
Expenditures for development and redevelopment properties and undeveloped land	(13,477)	(6,714)
Net proceeds received from dispositions of operating properties (Note 14)	100,765	0
Insurance proceeds received for property damage	951	0
Increase in acquisition-related deposits	(5,250)	(5,000)
Increase in restricted cash	(386)	(438)
Net cash used in investing activities	(97,084)	(61,137)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of Series G preferred stock (Note 7)	96,757	0
Net proceeds from issuance of common stock (Note 8)	382,063	0
Borrowings on unsecured line of credit	30,000	42,000
Repayments on unsecured line of credit	(212,000)	(144,000)
Proceeds from issuance of secured debt	0	135,000
Principal payments on secured debt	(1,546)	(1,598)
Proceeds from the issuance of unsecured debt (Note 5)	150,000	0
Financing costs	(1,877)	(1,160)
Decrease in loan deposits	0	2,027
Repurchase of common stock and restricted stock units (Note 10)	(603)	(732)
Proceeds from exercise of stock options	129	395
Dividends and distributions paid to common stockholders and common unitholders	(21,191)	(18,925)
Dividends and distributions paid to preferred stockholders and preferred unitholders	(3,799)	(3,799)
Net cash provided by financing activities	417,933	9,208
Net increase (decrease) in cash and cash equivalents	369,591	(8,132)
Cash and cash equivalents, beginning of period	4,777	14,840
Cash and cash equivalents, end of period	374,368	6,708
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $3,251 and $1,620 as of March 31, 2012 and 2011, respectively	4,487	6,965
NONCASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development and redevelopment properties	5,421	4,753
Tenant improvements funded directly by tenants to third parties	95	2,800
Assumption of other liabilities with property acquisitions (Note 2)	137	0
Net disposition proceeds held by a qualified intermediary in connection wtih Section 1031 exchange (Note 14)	42,395	0
NONCASH FINANCING TRANSACTIONS:
Accrual of preferred stock issuance costs	602	0
Accrual of dividends and distributions payable to common stockholders and common unitholders	24,524	18,950
Accrual of dividends and distributions payable to preferred stockholders and preferred unitholders	2,431	1,909
Issuance of share-based compensation awards (Note 10)	29,989	6,432
Reclassification of preferred stock called for redemption from equity to liabilities (Note 7)	$ 126,500	$ 0