Segment Reporting - Federal Government Segment Revenues by Customer Type (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenue from External Customer [Line Items]
Revenues	$ 3,980.4	$ 4,099.7	$ 4,450.6
Federal Government Business
Revenue from External Customer [Line Items]
Revenues	1,190.2	1,231.0	1,276.2
Federal Government Business | Department of Defense and Intelligence Agencies
Revenue from External Customer [Line Items]
Revenues	526.0	560.1	614.6
Federal Government Business | Federal Civilian
Revenue from External Customer [Line Items]
Revenues	224.9	267.2	261.6
Federal Government Business | Other
Revenue from External Customer [Line Items]
Revenues	129.3	124.3	123.8
Federal Government Business | National Security [Member]
Revenue from External Customer [Line Items]
Revenues	$ 310.0	$ 279.4	$ 276.2