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
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning Balance			$ 110,876
Net Income	1,082	874	3,385	2,440
Conversion of redeemable preferred units (Series Two Preferred Units) to common units				5,852
Ending Balance	67,806		67,806
Redeemable Preferred Units [Member]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning Balance			110,876	55,652
Issuance of redeemable preferred units (Series Four Preferred Units)				79,405
Net Income			3,385	2,440
Distributions			(3,385)	(2,440)
Conversion of redeemable preferred units (Series Two Preferred Units) to common units				(5,852)
Redemption of redeemable preferred units (Series Four Preferred Units)			43,070	18,329
Ending Balance	$ 67,806	$ 110,876	$ 67,806	$ 110,876