Segment and Geographic Information - Geographic Reporting Segments Table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Net sales: [Abstract]
Net sales	$ 2,145.7		$ 2,100.7
Income (loss) before income taxes: [Abstract]
Income (loss) before income taxes	4.1		5.7
Interest expense: [Abstract]
Interest expense	0.7		0.6
Depreciation and amortization: [Abstract]
Depreciation and amortization	6.6		6.3
United States
Net sales: [Abstract]
Net sales	1,905.6		1,818.5
Income (loss) before income taxes: [Abstract]
Income (loss) before income taxes	3.7		3.5
Interest expense: [Abstract]
Interest expense	6.9		6.4
Depreciation and amortization: [Abstract]
Depreciation and amortization	4.9		4.3
Canada
Net sales: [Abstract]
Net sales	232.2		274.6
Income (loss) before income taxes: [Abstract]
Income (loss) before income taxes	(0.3)		0.2
Interest expense: [Abstract]
Interest expense	0.3		0.2
Depreciation and amortization: [Abstract]
Depreciation and amortization	0.7		0.7
Corporate
Net sales: [Abstract]
Net sales	7.9	[1]	7.6	[1]
Income (loss) before income taxes: [Abstract]
Income (loss) before income taxes	0.7	[1]	2.0	[1]
Interest expense: [Abstract]
Interest expense	(6.5)	[1]	(6.0)	[1]
Depreciation and amortization: [Abstract]
Depreciation and amortization	$ 1.0	[1]	$ 1.3	[1]

[1] Corporate consists of net expenses and other income that is not allocated to the U.S. and Canada, intercompany eliminations for interest and allocations of overhead, service fee revenue for our consolidating warehouses, LIFO income or expense and reclassifying adjustments.