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Segment Reporting - Federal Government Segment Revenues by Customer Type (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Revenue from External Customer [Line Items]
Revenues	$ 4,099.7	$ 4,450.6	$ 4,581.1
Federal Government Business
Revenue from External Customer [Line Items]
Revenues	1,231.0	1,276.2	1,145.4
Federal Government Business | Department of Defense and Intelligence Agencies
Revenue from External Customer [Line Items]
Revenues	560.1	614.6	606.3
Federal Government Business | Federal Civilian
Revenue from External Customer [Line Items]
Revenues	627.4	621.6	503.4
Federal Government Business | Other
Revenue from External Customer [Line Items]
Revenues	$ 43.5	$ 40.0	$ 35.7

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