Condensed Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net sales	$ 2,287.3	$ 2,039.8	$ 4,388.0	$ 3,762.3
Cost of goods sold	2,164.7	1,930.0	4,155.2	3,560.2
Gross profit	122.6	109.8	232.8	202.1
Warehousing and distribution expenses	66.2	57.8	129.6	111.7
Selling, general and administrative expenses	37.8	36.5	77.5	73.2
Amortization of intangible assets	0.8	0.8	1.7	1.3
Total operating expenses	104.8	95.1	208.8	186.2
Income from operations	17.8	14.7	24.0	15.9
Interest expense	(0.6)	(0.6)	(1.2)	(1.2)
Interest income	0.1	0.1	0.2	0.2
Foreign currency transaction (losses) gains, net	(0.2)	0.2	(0.1)	0.8
Income before income taxes	17.1	14.4	22.9	15.7
Provision for income taxes	(7.0)	(5.9)	(9.2)	(6.7)
Net income	$ 10.1	$ 8.5	$ 13.7	$ 9.0
Basic net income per common share (in dollars per share)	$ 0.89	$ 0.74	$ 1.20	$ 0.79
Diluted net income per common share (in dollars per share)	$ 0.87	$ 0.72	$ 1.18	$ 0.76
Basic weighted-average shares	11.4	11.5	11.4	11.4
Diluted weighted-average shares	11.6	11.9	11.6	11.9
Dividend declared and paid per common share	$ 0.17	$ 0.00	$ 0.34	$ 0.00