Acquisitions and Dispositions Acquisitions and Dispositions - Pro Forma (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Actual revenue results included in consolidation									$ 330.7	$ 100.1
Actual net income results included in consolidation									18.4	10.0
Revenues	$ 907.7	$ 852.4	$ 849.7	$ 879.1	$ 903.2	$ 849.5	$ 805.9	$ 788.4	3,488.9	3,347.0	$ 3,020.6
Reported net income (loss) attributable to Brink's	34.9	$ 17.4	$ (107.9)	$ 22.3	(52.1)	$ 19.9	$ 14.2	$ 34.7	(33.3)	16.7	$ 34.5
Pro forma revenue results									3,734.3	3,857.2
Pro forma net income results									(27.6)	28.1
Transaction Costs	$ 6.7				$ 2.6				6.7	2.6
Dunbar
Business Acquisition [Line Items]
Actual revenue results included in consolidation									148.7	0.0
Actual net income results included in consolidation									2.4	0.0
Pro forma revenue results									244.0	386.6
Pro forma net income results									5.4	2.4
Maco
Business Acquisition [Line Items]
Actual revenue results included in consolidation									77.2	49.3
Actual net income results included in consolidation									13.1	7.8
Pro forma revenue results									0.0	56.9
Pro forma net income results									0.0	6.2
Other Acquisitions
Business Acquisition [Line Items]
Actual revenue results included in consolidation									104.8	50.8
Actual net income results included in consolidation									2.9	2.2
Pro forma revenue results									1.4	66.7
Pro forma net income results									$ 0.3	$ 2.8