Acquisitions and Dispositions - Pro Forma (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Business Acquisition [Line Items]
Actual revenue results included in consolidation	$ 38.0	$ 0.0	$ 106.2	$ 0.0
Actual net income results included in consolidation	(0.1)	0.0	0.0	0.0
Revenues	1,227.4	1,136.7	3,629.0	3,344.6
Net income (loss) attributable to Brink’s	45.6	19.2	92.7	125.6
Pro forma revenue results	1,227.4	1,172.7	3,629.0	3,453.8
Pro forma net income results	45.6	22.6	92.7	135.5
NoteMachine
Business Acquisition [Line Items]
Actual revenue results included in consolidation	38.0	0.0	106.2	0.0
Actual net income results included in consolidation	(0.1)	0.0	0.0	0.0
Pro forma revenue results	0.0	36.0	0.0	109.2
Pro forma net income results	$ 0.0	$ 3.4	$ 0.0	$ 9.9