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Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Segment Reporting Information [Line Items] |  |  |  |
Net sales | $ 4,373.2 | $ 3,933.2 | $ 12,165.7 | $ 11,080.8
Income (loss) from operations | 274.8 | 244.0 | 744.4 | 645.6
Depreciation and amortization expense | (65.8) | (65.7) | (198.7) | (195.2)
Operating Segments | Corporate |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net sales | 1,706.5 | 1,552.8 | 5,006.1 | 4,573.5
Income (loss) from operations | 127.2 | 121.6 | 393.3 | 360.6
Depreciation and amortization expense | (20.3) | (20.8) | (61.8) | (62.5)
Operating Segments | Small Business |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net sales | 340.0 | 305.4 | 997.1 | 912.4
Income (loss) from operations | 24.1 | 17.7 | 71.0 | 53.7
Depreciation and amortization expense | (5.2) | (5.2) | (15.6) | (15.4)
Operating Segments | Public |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net sales | 1,875.1 | 1,693.9 | 4,740.5 | 4,480.4
Income (loss) from operations | 138.0 | 122.3 | 322.7 | 287.6
Depreciation and amortization expense | (11.5) | (11.2) | (34.0) | (33.6)
Operating Segments | Other |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net sales | 451.6 | 381.1 | 1,422.0 | 1,114.5
Income (loss) from operations | 19.2 | 14.2 | 60.7 | 39.5
Depreciation and amortization expense | (7.3) | (8.0) | (25.1) | (22.7)
Headquarters |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net sales | 0.0 | 0.0 | 0.0 | 0.0
Income (loss) from operations | (33.7) | (31.8) | (103.3) | (95.8)
Depreciation and amortization expense | $ (21.5) | $ (20.5) | $ (62.2) | $ (61.0)

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