Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Disclosures [Abstract]

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

	December 31, 2012				December 31, 2011
	Carrying Amount		Fair Value		Carrying Amount			Fair Value
Mortgage notes payable	$	443,942	$	486,412	$	512,391		$	545,784
Unsecured notes payable	$	1,430,343	$	1,553,123	$	1,496,501		$	1,555,633
Variable rate debt	$	597,610	$	595,693	$	391,610		$	380,786
Notes receivable	$	7,226	$	7,783	$	31,157	(a)	$	32,756

(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 two properties in 2009 accounted for under the accounting standard for installment sales.