Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales	$ 4,502.6	$ 4,422.6	$ 12,705.8	$ 12,515.7
Cost of goods sold	4,267.6	4,176.0	12,039.3	11,822.0
Gross profit	235.0	246.6	666.5	693.7
Warehousing and distribution expenses	140.4	148.6	408.3	426.0
Selling, general and administrative expenses	57.3	61.8	181.0	192.3
Amortization of intangible assets	2.5	2.3	7.2	7.7
Total operating expenses	200.2	212.7	596.5	626.0
Income from operations	34.8	33.9	70.0	67.7
Interest expense, net	(2.1)	(4.2)	(8.4)	(10.8)
Foreign currency transaction (losses) gains, net	(0.5)	0.9	(0.7)	(0.3)
Income before income taxes	32.2	30.6	60.9	56.6
Provision for income taxes	(9.2)	(8.1)	(16.7)	(15.1)
Net income	$ 23.0	$ 22.5	$ 44.2	$ 41.5
Basic earnings per share (in dollars per share) (Note 6)	$ 0.51	$ 0.49	$ 0.98	$ 0.91
Diluted earnings per share (in dollars per share) (Note 6)	$ 0.51	$ 0.49	$ 0.98	$ 0.90
Basic weighted-average shares (in shares) (Note 6)	45.1	45.8	45.1	45.8
Diluted weighted-average shares (in shares) (Note 6)	45.4	46.1	45.3	46.1