SUPPLEMENTAL CASH FLOW DISCLOSURES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental disclosure:
Cash paid for interest, net of capitalized interest	$ 127,249	$ 126,267	$ 117,292
Interest capitalized	4,380	5,255	9,384
Non-cash investing and financing activities:
Note receivable converted to real estate	608
Mortgage loans assumed associated with property acquisitions	7,284		155,639
Mortgage note premium (discount) written off	(104)	(17)	270
Issuance of UPREIT Units associated with property acquisitions			4,845
Exchange of UPREIT Units for common shares	6,899	11,399	10,234
Transfers of construction in progress to buildings, improvements and equipment	42,732	100,266	110,902
Capital improvements to properties included in accounts payable	6,130	6,577	5,292
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