Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Net sales	$ 3,957.9	$ 3,606.4
Income (loss) from operations	228.9	204.1
Depreciation and amortization expense	(64.3)	(66.6)
Operating Segments \| Corporate
Segment Reporting Information [Line Items]
Net sales	1,736.2	1,565.8
Income (loss) from operations	134.7	123.0
Depreciation and amortization expense	(21.5)	(22.9)
Operating Segments \| Small Business
Segment Reporting Information [Line Items]
Net sales	355.6	327.6
Income (loss) from operations	24.4	21.9
Depreciation and amortization expense	(5.6)	(5.6)
Operating Segments \| Public
Segment Reporting Information [Line Items]
Net sales	1,330.7	1,230.0
Income (loss) from operations	76.1	70.2
Depreciation and amortization expense	(12.7)	(12.7)
Operating Segments \| Other
Segment Reporting Information [Line Items]
Net sales	535.4	483.0
Income (loss) from operations	25.6	19.8
Depreciation and amortization expense	(7.4)	(8.8)
Headquarters
Segment Reporting Information [Line Items]
Net sales	0.0	0.0
Income (loss) from operations	(31.9)	(30.8)
Depreciation and amortization expense	$ (17.1)	$ (16.6)

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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