Indebtedness (Tables)

6 Months Ended

Jun. 30, 2012

Debt Disclosure [Abstract]

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

	Book Value at 12/31/11		Book Value at 6/30/12		Fair Value at 12/31/11		Issuances and Assumptions		Payments/Payoffs			Adjustments to Fair Value		Fair Value at 6/30/12
Fixed rate secured debt	$	1,167,188	$	1,081,845	$	1,256,331	$	18,741	$	(102,869	)	$	3,952	$	1,176,155
Variable rate secured debt	6,045		19,350		6,045		13,305		—			498		19,848
Unsecured notes	2,616,063		2,915,155		2,834,610		300,000		(908		)	55,211		3,188,913
Unsecured lines of credit	20,293		20,293		20,244		—		—			36		20,280
Total	$	3,809,589	$	4,036,643	$	4,117,230	$	332,046	$	(103,777	)	$	59,697	$	4,405,196

Unsecured Lines of Credit

Description	Maximum Capacity		Maturity Date	Outstanding Balance at June 30, 2012
Unsecured Line of Credit - Partnership	$	850,000	December 2015	$	—
Unsecured Line of Credit - Consolidated Subsidiary	$	30,000	July 2012	$	20,293