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Goodwill and Identifiable Assets (Goodwill) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Goodwill [Roll Forward]
Beginning balance	$ 1,893.1	$ 1,894.1
Goodwill, Acquired During Period	245.9
Translation adjustment	0.5	(1.0)
Ending balance	2,139.5	1,893.1
Commercial
Goodwill [Roll Forward]
Beginning balance	1,074.8	1,075.8
Translation adjustment	0.5	(1.0)
Ending balance	1,321.2	1,074.8
Federal Government
Goodwill [Roll Forward]
Beginning balance	818.3	818.3
Ending balance	818.3	$ 818.3
2024 Acquisitions [Member] | Commercial
Goodwill [Roll Forward]
Goodwill, Acquired During Period	$ 245.9

X

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) asset representing future economic benefit from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

+ References

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Amount, before accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized. Includes amount, before amortization expense and impairment loss, of goodwill for private company.

+ References

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