Acquisitions and Dispositions - Pro Forma (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Actual revenue results included in consolidation	$ 142.3	$ 35.2
Actual net income results included in consolidation	(1.0)	2.1
Revenues	4,874.6	4,535.5	$ 4,200.2
Reported net income (loss) attributable to Brink's	87.7	170.6	$ 105.2
Pro forma revenue results	4,874.6	4,644.7
Pro forma net income results	87.7	180.5
NoteMachine
Business Acquisition [Line Items]
Actual revenue results included in consolidation	142.3	35.2
Actual net income results included in consolidation	(1.0)	2.1
Pro forma revenue results	0.0	109.2
Pro forma net income results	$ 0.0	$ 9.9