Indebtedness (Tables)

9 Months Ended

Sep. 30, 2013

Debt Disclosure [Abstract]

Fair Value, Liabilities Measured on a Recurring Basis, Disclosure Only

	Book Value at 12/31/12		Book Value at 9/30/13		Fair Value at 12/31/12		Issuances and Assumptions		Payments/Payoffs			Adjustments to Fair Value			Fair Value at 9/30/13
Fixed rate secured debt	$	1,149,541	$	1,139,262	$	1,251,477	$	103,638	$	(110,946	)	$	(23,801	)	$	1,220,368
Variable rate secured debt	18,412		19,194		18,386		1,933		(1,151		)	27			19,195
Unsecured debt	2,993,217		3,066,755		3,336,386		500,000		(426,462		)	(135,936		)	3,273,988
Unsecured line of credit	285,000		210,000		285,632		—		(75,000		)	403			211,035
Total	$	4,446,170	$	4,435,211	$	4,891,881	$	605,571	$	(613,559	)	$	(159,307	)	$	4,724,586

Unsecured Line of Credit

Description	Maximum Capacity		Maturity Date	Outstanding Balance at September 30, 2013
Unsecured Line of Credit - Partnership	$	850,000	December 2015	$	210,000