Fan Pier Leases (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2011 buildings area leases	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Y	Sep. 30, 2011
Fan Pier Leases
Number of leases	2
Area of leased property (in square feet)	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
Rent expense related to land operating lease		$ 1.6	$ 1.7	$ 5.0	$ 2.2