Noncontrolling Interests (Redeemable Preferred Units) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Activity of noncontrolling interests
Net income	$ 3,729	$ 874	$ 8,796	$ 2,440
Redeemable Preferred Units [Member]
Activity of noncontrolling interests
Beginning Balance			199,378	145,484
Issuance of redeemable preferred units (Series Four Preferred Units)				79,405
Net income				2,440
Contributions On Series Two Preferred Units			3,385
Distributions			(3,385)	(2,440)
Redemption of redeemable preferred units (Series Four Preferred Units)			(43,070)	(18,329)
Reallocation of partnership interest			1,425	(908)	[1]
Ending Balance	$ 157,733	$ 205,652	$ 157,733	$ 205,652

[1] Includes the conversion of 117,407 Series Two Preferred Units into 153,605 OP Units during the nine months ended September 30, 2012.