Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net sales	$ 8,892.4	$ 8,114.9	$ 7,266.8
Cost of goods sold	8,415.6	7,680.8	6,881.5
Gross profit	476.8	434.1	385.3
Warehousing and distribution expenses	262.7	234.6	211.8
Selling, general and administrative expenses	153.7	150.8	142.5
Amortization of intangible assets	3.0	3.0	2.1
Total operating expenses	419.4	388.4	356.4
Income from operations	57.4	45.7	28.9
Interest expense	(2.2)	(2.4)	(2.6)
Interest income	0.4	0.4	0.4
Foreign currency transaction (losses) gains, net	(0.2)	(0.5)	0.5
Income before income taxes	55.4	43.2	27.2
Provision for income taxes	(21.5)	(17.0)	(9.5)
Net income	$ 33.9	$ 26.2	$ 17.7
Basic net income per common share (in dollars per share)	$ 2.96	$ 2.30	$ 1.64
Diluted net income per common share (in dollars per share)	$ 2.91	$ 2.23	$ 1.55
Basic weighted-average shares (in shares)	11.5	11.4	10.8
Diluted weighted-average shares (in shares)	11.6	11.7	11.4
Dividends declared and paid per common share (in dollars per share)	$ 0.89	$ 0.17	$ 0.00