Long Term Obligations (Convertible Senior Subordinated Notes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Convertible Senior Subordinated Notes
Depreciation expense	$ 60.8	$ 60.0	$ 62.3
Rental expense	19.1	18.1	38.9
Buildings | Fan Pier Leases
Convertible Senior Subordinated Notes
Interest expense	60.2	60.2	60.2
Depreciation expense	13.3	13.3	13.4
Rental expense	$ 6.5	$ 6.5	$ 6.5