Property and Equipment (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 285.8	$ 233.1
Less: Accumulated depreciation and amortization	(136.9)	(118.2)
Total property and equipment, net	148.9	114.9
Depreciation and amortization expenses	21.5	20.0	18.5
Delivery, warehouse and office equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	208.4	169.0
Equipment capital leases [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8.0	3.3
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	44.3	36.1
Land and buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	27.9	26.9
Land and buildings - Warehouse facility capital lease [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4.8	4.8
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 5.2	$ 1.1