Other Assets (Other Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Assets
Deferred compensation plan	$ 99.9	$ 87.9
Amounts recoverable for capping, closure and post-closure obligations	29.9	27.7
Reinsurance receivable	65.9	69.7
Interest rate swaps and locks - other assets	27.1	32.4
Investments	26.0	24.8
Other	86.4	78.0
Total	$ 335.2	$ 320.5