Acquisitions and Dispositions Acquisitions and Dispositions - Pro Forma (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Actual revenue results included in consolidation									$ 82.1
Actual net income results included in consolidation									4.8
Revenues	$ 935.8	$ 928.4	$ 914.0	$ 905.0	$ 907.7	$ 852.4	$ 849.7	$ 879.1	3,683.2	$ 3,488.9	$ 3,347.0
Reported net income (loss) attributable to Brink's	(2.6)	$ 5.4	$ 12.5	$ 13.7	34.9	$ 17.4	$ (107.9)	$ 22.3	29.0	(33.3)	16.7
Pro forma revenue results									3,710.6	3,854.3
Pro forma net income results									30.6	(29.9)
Transaction Costs	$ 7.9				$ 6.7				7.9	6.7	$ 2.6
Rodoban
Business Acquisition [Line Items]
Actual revenue results included in consolidation									66.0
Actual net income results included in consolidation									4.6
Pro forma revenue results									0.6	76.0
Pro forma net income results									0.0	(3.9)
Dunbar
Business Acquisition [Line Items]
Pro forma revenue results										244.0
Pro forma net income results										5.4
Other Acquisitions
Business Acquisition [Line Items]
Actual revenue results included in consolidation									16.1
Actual net income results included in consolidation									0.2
Pro forma revenue results									26.8	45.4
Pro forma net income results									$ 1.6	$ 1.9