Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012 Property	Dec. 31, 2011
Commitments and Contingencies (Textual) [Abstract]
Commitments related to capital spending activities	$ 53.4
Number of consolidated properties	2
Term of commitments to purchase goods or services related to the operations of properties	one year or less
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	30.9
Assumption of property debt required for acquisition of certain properties that collateralize our notes receivable upon the obligor's exercise of put option	118.3
Range of remaining compliance periods for tax credit syndication arrangements	less than one year to 14 years
Amount of additional consideration accrued for purchase of noncontrolling interests in consolidated real estate partnerships		$ 7.5