Accounting Policies (Property and Equipment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Land	$ 254.4	$ 257.5
Structures	789.3	784.3
Revenue equipment	1,430.1	1,431.9
Technology equipment and software	146.4	148.2
Other	202.6	197.7
Total cost	2,822.8	2,819.6
Depreciation	$ 145.5	$ 145.1	$ 153.8
Structures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, service life	10 years
Structures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, service life	30 years
Revenue equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, service life	10 years
Revenue equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, service life	20 years
Technology equipment and software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, service life	3 years
Technology equipment and software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, service life	7 years
Other [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, service life	3 years
Other [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, service life	10 years