Income Taxes (Deferred tax liabilities and assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Depreciation	$ 327.8	$ 375.2
Deferred revenue	12.2	12.4
Intangibles	36.3	45.5
Gain on debt redemption	63.9	64.5
Other	54.8	46.6
Deferred tax liabilities	495.0	544.2
Claims and insurance	(179.6)	(204.6)
Net operating loss carryforwards	(298.8)	(230.5)
Employee benefit accruals	(288.9)	(238.2)
Other	(173.6)	(207.4)
Deferred tax assets	(940.9)	(880.7)
Valuation allowance	448.4	336.6
Net deferred tax assets	(492.5)	(544.1)
Net deferred tax liability	$ 2.5	$ 0.1