Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 25.5	$ 40.5
Benefit plan adjustments:
Benefit plan actuarial gains	14.8	11.8
Benefit plan prior service cost	(0.8)	(0.5)
Total benefit plan adjustments	14.0	11.3
Foreign currency translation adjustments	1.0	27.2
Unrealized net gains on available-for-sale securities	0.0	0.2
Gains on cash flow hedges	0.4	0.0
Other comprehensive income before tax	15.4	38.7
Provision for income taxes	3.2	4.4
Other comprehensive income	12.2	34.3
Comprehensive income	37.7	74.8
Less comprehensive income attributable to noncontrolling interests	4.3	6.9
Comprehensive income attributable to Brink's	$ 33.4	$ 67.9