Supplemental Information to Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Interest Expense Capitalized in Connection with Development Activity	$ 1,623	$ 473
Mortgage Loan Payable Assumed in Conjunction with a Property Acquisition	0	12,026
Write-off of Fully Depreciated Assets	(29,561)	(23,135)
Supplemental Schedule of Non-Cash Investing and Financing Activities:
Distribution payable	11,801
Exchange of Limited Partnership Units for General Partnership Units:
Conversion of Limited Partner Units to General Partner Units	0	0
Limited Partnership Units
Exchange of Limited Partnership Units for General Partnership Units:
Conversion of Limited Partner Units to General Partner Units	(804)	(2,469)
General Partnership Units
Exchange of Limited Partnership Units for General Partnership Units:
Conversion of Limited Partner Units to General Partner Units	804	2,469
General and Limited Partner Units
Supplemental Schedule of Non-Cash Investing and Financing Activities:
Distribution payable	9,745	0
Preferred Units
Supplemental Schedule of Non-Cash Investing and Financing Activities:
Distribution payable	$ 2,056	$ 4,798