Supplemental Cash Flow Disclosures (Supplemental Cash Flow Information Including Non-Cash Financing And Investing Activities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash paid for interest, net of capitalized interest	$ 126,267	$ 117,292	$ 121,800
Interest capitalized	5,255	9,384	8,900
Mortgage loans assumed associated with property acquisitions		155,639
Mortgage note premium written off	(17)	270	1,921
Issuance of UPREIT Units associated with property acquisitions		4,845
Exchange of UPREIT Units for common shares	0	0	0
Transfers of construction in progress to buildings, improvements and equipment	100,266	110,902
Additions to properties included in accounts payable	6,577	5,292	2,210
Net real estate disposed in connection with VIE deconsolidation		13,837
Other assets disposed in connection with VIE deconsolidation		1,228
Mortgage debt disposed in connection with VIE deconsolidation		15,762
Other liabilities disposed in connection with VIE deconsolidation		1,031
Noncontrolling Interest [Member]
Issuance of UPREIT Units associated with property acquisitions		4,845
Exchange of UPREIT Units for common shares	$ 11,399	$ 10,234	$ 21,332