Commitments and Contingencies (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Commitments and Contingencies (Textual) [Abstract]
Commitments related to capital spending activities	$ 9.6
Term of commitments to purchase goods or services related to the operations of properties	one year or less
Rent expense	5.4	6.6	7.7
Sublease income which offset rent expense	0.8	1.6	0.7
Commitment to advance funds	3.0
Maximum cash payment required for acquisition of certain properties that collateralize our notes receivable upon the obligor's exercise of put option	30.8
Assumption of property debt required for acquisition of certain properties that collateralize our notes receivable upon the obligor's exercise of put option	118.4
Amount of additional consideration accrued for purchase of noncontrolling interests in consolidated real estate partnerships	7.5
Range of remaining compliance periods for tax credit syndication arrangements	less than one year to 14 years
Future operating lease payments included in restructuring reserve	$ 1.5	$ 4.7