Investment in Real Estate (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Summary of net non-cash impairment charges
Total Net Impairment	$ 1,246	$ (52)
Operating Properties - Held for Sale and Sold Assets [Member]
Summary of net non-cash impairment charges
Total Net Impairment	(1,260)	(2,727)
Impairment - Discontinued Operations [Member]
Summary of net non-cash impairment charges
Total Net Impairment	(1,260)	(2,727)
Land Parcels - Held for Sale and Sold Assets [Member]
Summary of net non-cash impairment charges
Total Net Impairment
Operating Properties - Held for Use [Member]
Summary of net non-cash impairment charges
Total Net Impairment	14	2,184
Land Parcels - Held for Use [Member]
Summary of net non-cash impairment charges
Total Net Impairment		595
Impairment - Continuing Operations [Member]
Summary of net non-cash impairment charges
Total Net Impairment	$ 14	$ 2,779