Segment and Geographic Information - Information by Geographic Areas (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net sales	$ 2,810.4	$ 2,623.2	$ 5,262.7	$ 4,924.1
Income (loss) before income taxes	21.4	19.9	30.5	23.9
Interest expense	0.7	0.6	1.3	1.3
Depreciation and amortization	9.7	7.9	18.4	15.1
Capital expenditures	11.7	9.8	14.4	14.8
Reportable Geographical Components [Member] | United States
Segment Reporting Information [Line Items]
Net sales	2,479.2	2,294.3	4,655.3	4,333.4
Income (loss) before income taxes	22.2	19.8	28.7	23.0
Interest expense	8.6	7.8	16.8	15.3
Depreciation and amortization	7.5	6.2	14.2	11.7
Capital expenditures	11.3	9.5	13.9	14.4
Reportable Geographical Components [Member] | Canada
Segment Reporting Information [Line Items]
Net sales	324.1	319.9	591.9	575.9
Income (loss) before income taxes	(0.4)	0.7	(0.6)	0.4
Interest expense	0.2	0.1	0.4	0.4
Depreciation and amortization	0.7	0.7	1.3	1.4
Capital expenditures	0.4	0.3	0.5	0.4
Corporate [Member]
Segment Reporting Information [Line Items]
Net sales	7.1	9.0	15.5	14.8
Income (loss) before income taxes	(0.4)	(0.6)	2.4	0.5
Interest expense	(8.1)	(7.3)	(15.9)	(14.4)
Depreciation and amortization	$ 1.5	$ 1.0	$ 2.9	$ 2.0