Segment Reporting - Segment Reporting Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 4,581.1	$ 4,009.5	$ 3,502.1
Gross Profit	1,369.6	1,142.4	947.2
Operating Income (Loss)	409.5	350.9	281.2
Depreciation	26.3	28.0	28.3
Amortization	65.1	55.7	51.0
Commercial Business
Segment Reporting Information [Line Items]
Revenues	3,435.7	2,927.1	2,497.9
Gross Profit	1,126.2	934.9	778.3
Operating Income (Loss)	411.1	355.9	284.5
Depreciation	16.3	13.9	14.4
Amortization	31.3	25.7	22.9
Federal Government Business
Segment Reporting Information [Line Items]
Revenues	1,145.4	1,082.4	1,004.2
Gross Profit	243.4	207.6	168.9
Operating Income (Loss)	89.1	76.1	58.0
Depreciation	5.5	8.5	9.0
Amortization	$ 33.8	$ 30.0	$ 28.1