Summary of Significant Accounting Policies Summary of Significant Accounting Policies Text (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Value of furniture and fixtures minimum range	$ 3,000
Value of furniture and fixtures maximum range	13,000
Deferred Tax Assets, Gross	36,100,000
Partially Owned Consolidated Properties	20
Partially Owned Consolidated Units	3,917
Noncontrolling Interests - Partially Owned Properties	105,930,000	77,688,000
Partially Owned Limited Life Partnership Properties	6
Noncontrolling Interest Balance Limited Life Partnerships	8,000,000
Noncontrolling Interests Settlement Value	$ 35,500,000
Furniture and Fixtures [Member]
Property, Plant and Equipment, Estimated Useful Lives	5
Building Improvements [Member]
Property, Plant and Equipment, Estimated Useful Lives	8
Furniture and Fixtures Maximum [Member]
Property, Plant and Equipment, Estimated Useful Lives	10
Building [Member]
Property, Plant and Equipment, Estimated Useful Lives	30