Commitments to Acquire/Dispose of Real Estate (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013
Commitments to Acquire Real Estate
Properties Acquired-Total	0
Rental Units Acquired - Total	0
Purchase Price - Total	$ 12,500
Commitments to Dispose of Real Estate
Properties Disposed - Total	7
Rental Units Disposed-Total	1,566
Sales Price For Commitments To Dispose	247,115
Land Parcel [Member]
Land Parcels Contracted to be Acquired	1
Commitments to Acquire Real Estate
Purchase Price - Total	12,500
Commercial Properties Disposed of [Domain]
Commitments to Dispose of Real Estate
Area of Real Estate Property	97,000
Rental Properties Disposed of [Member]
Commitments to Dispose of Real Estate
Properties Disposed - Total	7
Rental Units Disposed-Total	1,566
Sales Price For Commitments To Dispose	191,715
Land Parcel [Member]
Commitments to Dispose of Real Estate
Sales Price For Commitments To Dispose	22,900
Land Parcels Contracted to be Disposed	2
Other Property [Member]
Commitments to Dispose of Real Estate
Sales Price For Commitments To Dispose	$ 32,500
Commercial Property Contracted to be Disposed	1