Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 18.8	$ 21.1	$ (63.3)	$ 75.1
Benefit plan adjustments:
Benefit plan actuarial gains	13.5	9.6	51.2	32.5
Benefit plan prior service credits (costs)	(0.9)	(0.4)	(0.6)	(1.6)
Deferred profit sharing	0.1	0.0	0.1	0.1
Total benefit plan adjustments	12.7	9.2	50.7	31.0
Foreign currency translation adjustments	(0.6)	16.5	(31.4)	49.4
Unrealized net gains (losses) on available-for-sale securities	0.0	(0.3)	0.0	0.4
Gains (losses) on cash flow hedges	0.0	0.0	0.6	(0.1)
Other comprehensive income before tax	12.1	25.4	19.9	80.7
Provision for income taxes	3.1	3.7	10.1	12.5
Other comprehensive income	9.0	21.7	9.8	68.2
Comprehensive income (loss)	27.8	42.8	(53.5)	143.3
Less comprehensive income attributable to noncontrolling interests	1.4	3.3	5.0	7.7
Comprehensive income (loss) attributable to Brink's	$ 26.4	$ 39.5	$ (58.5)	$ 135.6