Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 21.9	$ 33.2	$ (27.5)
Benefit plan adjustments:
Benefit plan actuarial gains (losses)	(37.0)	27.1	35.4
Benefit plan prior service costs	(5.3)	(4.1)	(1.6)
Deferred profit sharing	0.7	0.4	(0.2)
Total benefit plan adjustments	(41.6)	23.4	33.6
Foreign currency translation adjustments	24.2	(0.1)	(45.2)
Gains (losses) on cash flow hedges	(11.2)	(19.0)	0.1
Other comprehensive income (loss) before tax	(28.6)	4.3	(11.5)
Provision (benefit) for income taxes	(12.4)	0.4	5.0
Other comprehensive income (loss)	(16.2)	3.9	(16.5)
Comprehensive income (loss)	5.7	37.1	(44.0)
Less comprehensive income attributable to noncontrolling interests	10.7	5.0	5.0
Comprehensive income (loss) attributable to Brink’s	$ (5.0)	$ 32.1	$ (49.0)