Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 26.9	$ 15.2	$ 42.3	$ 18.0
Benefit plan adjustments:
Benefit plan actuarial gains	14.6	13.2	14.4	31.8
Benefit plan prior service costs	(0.5)	(1.3)	(1.8)	(2.4)
Total benefit plan adjustments	14.1	11.9	12.6	29.4
Foreign currency translation adjustments	37.9	28.2	(8.1)	(92.1)
Gains (losses) on cash flow hedges	2.7	(2.6)	9.9	(17.3)
Other comprehensive income (loss) before tax	54.7	37.5	14.4	(80.0)
Provision for income taxes	5.2	2.3	7.7	2.2
Other comprehensive income (loss)	49.5	35.2	6.7	(82.2)
Comprehensive income (loss)	76.4	50.4	49.0	(64.2)
Less comprehensive income attributable to noncontrolling interests	3.3	3.3	3.9	3.9
Comprehensive income (loss) attributable to Brink's	$ 73.1	$ 47.1	$ 45.1	$ (68.1)