Supplemental Disclosure to Statements of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Disclosure to Statements of Cash Flows [Abstract]
Write-off of fully depreciated property and deferred costs	$ 22,269	$ 31,069	$ 16,591
Write Off Of Depreciated Property And Deferred Costs Due To Sale	202,695	106,698	110,414
Write-off of preferred units costs due to redemption	1,214	2,806	0
Assumption of mortgage loans in connection with the acquisition of properties	(229,751)	(12,537)	0
Equity contribution from unconsolidated joint venture partner	0	0	3,500
Issuance of preferred units, noncash transaction	0	0	16,597
Unrealized gains on cash flow hedge, non cash transaction	$ 1,584	$ 0	$ 0