Income Taxes (Deferred Income Tax Asset and Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax liabilities relating to:
Differences between book and tax basis of property and equipment	$ (799.9)	$ (715.3)
Difference between book and tax basis of intangible assets	(453.3)	(446.9)
Basis difference due to redemption of partnership interests	(88.8)	(89.0)
Total liabilities	(1,342.0)	(1,251.2)
Deferred tax assets relating to:
Environmental reserves	253.2	272.5
Accruals not currently deductible	78.9	106.2
Net operating loss carryforwards	134.3	143.3
Difference between book and tax basis of other assets	13.7	27.3
Other	12.9	14.4
Total assets	493.0	563.7
Valuation allowance	(73.5)	(72.4)
Net deferred tax asset	419.5	491.3
Net deferred tax liabilities	$ (922.5)	$ (759.9)