Acquisitions (Assets Acquired Liabilities Assumed) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Apr. 30, 2012 Outlet Shoppes at El Paso and El Paso Outparcels [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Land	$ 87,869	$ 2,330
Buildings and improvements	379,763	8,220
Investments in unconsolidated affiliates	3,864	0
Tenant improvements	15,328	0
Above-market leases	15,359	2,030
In-place leases	65,814	1,570
Total assets	567,997	14,150
Mortgage note payables assumed	259,470	0	(66,924)
Debt premium	15,334	0
Below-market leases	39,698	2,650
Noncontrolling interest	60,295	0
Value of Company's interest in joint ventures	65,494	0
Net assets acquired	$ 127,706	$ 11,500	$ 116,775