Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Rental costs
Rent expense	$ 44.3	$ 43.4	$ 35.1
Letters of credit, outstanding	7.2	7.8
Unconsolidated real estate affiliates
Rental costs
Rent expense	$ 7.1	$ 8.6	$ 5.4
Minimum
Commitments and Contingencies
Lease term (in years)	1
Maximum
Commitments and Contingencies
Lease term (in years)	14