Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net sales	$ 3,939.3	$ 3,754.1
Cost of goods sold	3,720.9	3,545.9
Gross profit	218.4	208.2
Warehousing and distribution expenses	142.4	134.2
Selling, general and administrative expenses	63.9	65.9
Amortization of intangible assets	2.3	2.7
Total operating expenses	208.6	202.8
Income from operations	9.8	5.4
Interest expense, net	(3.5)	(3.4)
Foreign currency transaction losses, net	(0.2)	(0.2)
Income before income taxes	6.1	1.8
Provision for income taxes	(1.8)	(0.5)
Net income	$ 4.3	$ 1.3
Basic and diluted earnings per share (in dollars per share) (Note 6)	$ 0.09	$ 0.03
Basic weighted-average shares (in shares) (Note 6)	45.3	45.9
Diluted weighted-average shares (in shares) (Note 6)	45.4	46.0