Interest and Other Nonoperating Income (Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Interest and Other Income [Abstract]
Interest income	$ 23.6	$ 12.1	$ 5.6
Retirement benefit cost other than service cost	(16.7)	(38.7)	(37.9)
Foreign currency transaction gains (losses)(a)	2.4	0.4	(3.6)
Non-income taxes on intercompany billings	(2.3)	(3.9)	(4.6)
Argentina turnover tax	(1.8)
Gain (loss) on equity securities	0.0	16.0	10.6
G4S indemnification asset adjustment	0.0	2.7
Penalties and interest on non-income taxes	0.0	(1.8)
Gains related to litigation	0.0	1.7
Earn-out liability adjustment	0.0	1.3
Interest on non-income tax credits	0.0	1.2
Derivative instrument losses	0.0	0.0	(7.0)
Gain on a disposition of a subsidiary	0.0	0.0	(4.1)
Other	(1.5)	2.0	(4.9)
Interest and other nonoperating income (expense)	$ 3.7	$ (7.0)	$ (37.7)