Property, Plant and Equipment (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Principal Accounting Policies [Line Items]
Depreciation expense	$ 232.4	$ 221.2	$ 204.9
Buildings [Member]
Principal Accounting Policies [Line Items]
Property, plant and equipment, useful lives, years	25 years
Minimum [Member] | Revenue Equipment [Member]
Principal Accounting Policies [Line Items]
Property, plant and equipment, useful lives, years	4 years
Minimum [Member] | Other equipment [Member]
Principal Accounting Policies [Line Items]
Property, plant and equipment, useful lives, years	3 years
Minimum [Member] | Software and Software Development Costs [Member]
Principal Accounting Policies [Line Items]
Property, plant and equipment, useful lives, years	3 years
Maximum [Member] | Revenue Equipment [Member]
Principal Accounting Policies [Line Items]
Property, plant and equipment, useful lives, years	14 years
Maximum [Member] | Other equipment [Member]
Principal Accounting Policies [Line Items]
Property, plant and equipment, useful lives, years	10 years
Maximum [Member] | Software and Software Development Costs [Member]
Principal Accounting Policies [Line Items]
Property, plant and equipment, useful lives, years	7 years