Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, Percent			17.50%	(113.70%)	31.30%
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act of 2017, Amount			$ 16.5	$ 315.9	$ 0.0
Deferred Tax Liabilities
Book/tax basis difference due to depreciation	$ 890.7	$ 872.8	890.7	872.8
Investments in affiliated companies	36.2	43.6	36.2	43.6
Lease accounting (other than leveraged)	12.2	9.0	12.2	9.0
Other	1.9	6.3	1.9	6.3
Total deferred tax liabilities	941.0	931.7	941.0	931.7
Deferred Tax Assets
Alternative minimum tax credit	3.4	8.0	3.4	8.0
Federal net operating loss	0.0	4.1	0.0	4.1
State net operating loss	26.4	29.5	26.4	29.5
Valuation on state net operating loss	(12.6)	(10.3)	(12.6)	(10.3)
Foreign net operating loss	2.1	2.1	2.1	2.1
Deferred Tax Assets, Valuation Allowance	(0.3)	(0.4)	(0.3)	(0.4)
Accruals not currently deductible for tax purposes	24.8	21.7	24.8	21.7
Allowance for losses	1.1	1.1	1.1	1.1
Pension and post-retirement benefits	17.8	19.6	17.8	19.6
Other	0.5	2.6	0.5	2.6
Total deferred tax assets	63.2	78.0	63.2	78.0
Net deferred tax liabilities	877.8	853.7	877.8	853.7
Gross liability for unrecognized tax benefits
Ending balance	4.3		4.3
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount			1.4	0.0	$ 7.8
Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Income Tax Expense (Benefit)				371.4
Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Deferred Tax Liability, Income Tax (Expense) Benefit				5.0
Tax Cuts and Jobs Act of 2017, Transition Tax for Accumulated Foreign Earnings, Income Tax Expense (Benefit)			$ 23.1	$ 57.2
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent			26.70%	33.70%	33.90%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	17.9	$ 315.9	$ 9.4	$ (371.4)	$ 0.0
Provision for Income Taxes, Equity Method Investment			10.8	$ 12.0	$ 5.7
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 1.8		$ 1.8