Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2011

Fair Value Disclosures [Abstract]

Schedule of financial instruments with fair values different from their carrying amount

	December 31, 2011					December 31, 2010
	Carrying Amount			Fair Value		Carrying Amount			Fair Value
Mortgage payable, net of premiums	$	512,391		$	545,784	$	712,246		$	726,348
Unsecured notes payable, net of discounts	$	1,496,501		$	1,555,633	$	1,277,716		$	1,338,743
Variable Rate Debt Instruments	$	391,610		$	380,786	$	444,610		$	432,556
Notes Receivable	$	31,157	(a)	$	32,756	$	31,216	(a)	$	28,921

(a) For purposes of this disclosure, one of the notes is presented gross of the deferred gain of $12.9 million arising from the sale of the two Trenton properties in 2009 accounted for under the accounting standard for installment sales.