Interest and Other Nonoperating Income (Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investment [Line Items]
Interest income	$ 12.1	$ 5.6	$ 5.6
Gain (loss) on equity securities	16.0	10.6	(2.9)
Foreign currency transaction losses	0.4	(3.6)	0.0
Derivative instrument losses	0.0	(7.0)	0.0
Retirement benefit cost other than service cost	(38.7)	(37.9)	(52.7)
G4S indemnification asset adjustment	2.7
Acquisition-related gains (losses)	0.4
Penalties and interest on non-income taxes	(1.8)
Interest on Colombia tax claim	0.0	0.0	(1.1)
Non-income taxes on intercompany billings	(3.9)	(4.6)	(4.2)
Venezuela operations	0.0	0.0	(0.9)
Gain on lease termination	0.0	0.0	5.2
Gain on a disposition of a subsidiary	0.0	(4.1)	0.0
Interest on non-income tax credits	1.2
Earn-out liability adjustment	1.3
Gains related to litigation	1.7
Other	1.6	(4.9)	(1.7)
Interest and other nonoperating income (expense)	$ (7.0)	$ (37.7)	(52.7)
COLOMBIA
Investment [Line Items]
Tax claim			$ 1.0