Fan Pier Leases (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	May 31, 2011 buildings leases squarefeet	Dec. 31, 2011 Y squarefeet leases
Fan Pier Leases
Number of leases	2	2
Area of leased property (in square feet)	1,100,000	1,100,000
Number of buildings under lease agreement	2
Initial term of lease agreement (in years)		15
Optional term of lease agreement (in years)		10
Project construction costs		$ 54.7
Rent expense related to land operating lease		$ 3.9