Consolidated Statements Of Cash Flows (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities:
Net income (loss)	$ 50,931	$ (17,992)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation of buildings and tenant improvements	135,809	130,236
Amortization of deferred leasing and other costs	59,285	35,937
Amortization of deferred financing costs	7,351	7,092
Straight-line rent adjustment	(11,887)	(9,083)
Impairment charges		7,974
Loss on debt extinguishment		16,127
Earnings from land and depreciated property sales	(82,664)	(19,898)
Third-party construction contracts, net	(25,658)	(17,407)
Other accrued revenues and expenses, net	264	12,737
Operating distributions received in excess of equity in earnings from unconsolidated companies	10,862	2,597
Net cash provided by operating activities	144,293	148,320
Cash flows from investing activities:
Development of real estate investments	(78,645)	(56,762)
Acquisition of real estate investments and related intangible assets, net of cash acquired	(99,817)	(19,205)
Acquisition of undeveloped land		(4,706)
Second generation tenant improvements, leasing costs and building improvements	(41,284)	(34,805)
Other deferred leasing costs	(13,807)	(16,752)
Other assets	3,149	(28,699)
Proceeds from land and depreciated property sales, net	498,249	151,835
Capital distributions from unconsolidated companies	54,730	3,897
Capital contributions and advances to unconsolidated companies, net	(16,917)	(16,577)
Net cash provided by (used for) investing activities	305,658	(21,774)
Cash flows from financing activities:
Contributions from the General Partner		298,066
Payments for repurchases of Preferred Units	(2,096)	(58,304)
Proceeds from unsecured debt issuance		250,000
Payments on and repurchases of unsecured debt	(43,377)	(387,860)
Proceeds from secured debt financings		4,160
Payments on secured indebtedness including principal amortization	(7,968)	(5,317)
Borrowings (payments) on lines of credit, net	(174,717)	313
Distributions to common unitholders	(88,219)	(78,528)
Distributions to preferred unitholders	(31,948)	(36,726)
Distributions to noncontrolling interests	(58)	(1,631)
Deferred financing costs	(2,342)	(1,970)
Net cash used for financing activities	(350,725)	(17,797)
Net increase in cash and cash equivalents	99,226	108,749
Cash and cash equivalents at beginning of period	18,419	147,539
Cash and cash equivalents at end of period	117,645	256,288
Non-cash investing and financing activities:
Assumption of indebtedness for real estate acquisitions	130,474	4,503
Contribution of properties to unconsolidated companies	52,868	7,002
Conversion of Limited Partner Units to common shares of the General Partner	1,235	4,335
Issuance of Limited Partner Units for acquisition	$ 28,357