Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Net sales	$ 5,976.6	$ 5,423.4	$ 11,175.7	$ 10,296.1
Cost of sales	4,735.4	4,240.3	8,812.2	8,049.7
Gross profit	1,241.2	1,183.1	2,363.5	2,246.4
Other segment expense items	821.0	750.0	1,581.9	1,485.3
Operating income	420.2	433.1	781.6	761.1
Depreciation and amortization expense	73.3	69.4	148.2	136.7
Corporate
Segment Reporting Information [Line Items]
Net sales	2,581.5	2,195.2	4,817.5	4,331.1
Small Business
Segment Reporting Information [Line Items]
Net sales	431.3	382.9	835.9	763.8
Public
Segment Reporting Information [Line Items]
Net sales	2,291.7	2,243.3	4,169.8	3,968.0
Other
Segment Reporting Information [Line Items]
Net sales	672.1	602.0	1,352.5	1,233.2
Operating Segments | Corporate
Segment Reporting Information [Line Items]
Net sales	2,581.5	2,195.2	4,817.5	4,331.1
Cost of sales	2,009.0	1,672.1	3,710.1	3,300.5
Gross profit	572.5	523.1	1,107.4	1,030.6
Other segment expense items	329.4	326.1	643.6	655.6
Operating income	243.1	197.0	463.8	375.0
Depreciation and amortization expense	24.9	19.3	52.3	39.1
Operating Segments | Small Business
Segment Reporting Information [Line Items]
Net sales	431.3	382.9	835.9	763.8
Cost of sales	336.7	295.2	652.7	586.3
Gross profit	94.6	87.7	183.2	177.5
Other segment expense items	46.8	42.1	92.0	85.4
Operating income	47.8	45.6	91.2	92.1
Depreciation and amortization expense	1.6	0.8	3.0	1.8
Operating Segments | Public
Segment Reporting Information [Line Items]
Net sales	2,291.7	2,243.3	4,169.8	3,968.0
Cost of sales	1,859.6	1,791.6	3,371.1	3,171.0
Gross profit	432.1	451.7	798.7	797.0
Other segment expense items	244.6	242.5	470.0	461.8
Operating income	187.5	209.2	328.7	335.2
Depreciation and amortization expense	15.9	14.3	31.6	27.7
Operating Segments | Other
Segment Reporting Information [Line Items]
Net sales	672.1	602.0	1,352.5	1,233.2
Cost of sales	530.1	481.4	1,078.3	991.9
Gross profit	142.0	120.6	274.2	241.3
Other segment expense items	99.4	96.4	192.5	191.8
Operating income	42.6	24.2	81.7	49.5
Depreciation and amortization expense	7.1	7.1	13.9	14.2
Headquarters
Segment Reporting Information [Line Items]
Net sales	0.0	0.0	0.0	0.0
Cost of sales	0.0	0.0	0.0	0.0
Gross profit	0.0	0.0	0.0	0.0
Other segment expense items	100.8	42.9	183.8	90.7
Operating income	(100.8)	(42.9)	(183.8)	(90.7)
Depreciation and amortization expense	$ 23.8	$ 27.9	$ 47.4	$ 53.9