Acquisitions Acquisitions - Pro Forma (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Actual revenue results included in consolidation									$ 100.1
Actual net income results included in consolidation									10.0
Revenues	$ 903.2	$ 849.5	$ 805.9	$ 788.4	$ 803.5	$ 755.8	$ 739.5	$ 721.8	3,347.0	$ 3,020.6	$ 3,061.4
Reported net income attributable to Brink's	(52.1)	$ 19.9	$ 14.2	$ 34.7	$ 12.8	$ 24.5	$ 0.3	$ (3.1)	16.7	34.5	$ (11.9)
Pro forma revenue results									3,469.6	3,198.1
Pro forma net income results									25.5	45.9
Transaction Costs	$ 2.6								2.6
Maco
Business Acquisition [Line Items]
Actual revenue results included in consolidation									49.3
Actual net income results included in consolidation									7.8
Pro forma revenue results									56.9	79.5
Pro forma net income results									6.2	6.2
Other Acquisitions
Business Acquisition [Line Items]
Actual revenue results included in consolidation									50.8
Actual net income results included in consolidation									2.2
Pro forma revenue results									65.7	98.0
Pro forma net income results									$ 2.6	$ 5.2