Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 31.9	$ 49.4	$ 133.9	$ 102.8
Net benefit plan adjustments:
Net benefit plan actuarial adjustment	1.6	4.2	10.9	7.3
Net benefit plan prior service adjustment	(2.3)	(2.8)	(15.5)	(8.5)
Net deferred profit sharing adjustment	0.1	(0.2)	0.0	0.1
Total benefit plan adjustments	(0.6)	1.2	(4.6)	(1.1)
Net foreign currency translation adjustment	15.1	(41.0)	(77.5)	18.1
Net change on available-for-sale securities	(6.1)	7.9	(4.4)	8.3
Net change on cash flow hedges	(21.6)	6.9	(10.0)	13.9
Other comprehensive income (loss) before tax	(13.2)	(25.0)	(96.5)	39.2
Provision (benefit) for income taxes	(10.5)	5.7	(3.1)	3.6
Other comprehensive income (loss)	(2.7)	(30.7)	(93.4)	35.6
Comprehensive income	29.2	18.7	40.5	138.4
Less comprehensive income attributable to noncontrolling interests	10.0	2.3	13.8	5.8
Comprehensive income attributable to Brink's	$ 19.2	$ 16.4	$ 26.7	$ 132.6