Capital Stock (Details) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Sep. 19, 2024	Jul. 11, 2024	Nov. 02, 2023	Oct. 27, 2021
Equity, Class of Treasury Stock [Line Items]
Shares of common stock authorized (in shares)		100,000,000		100,000,000.0
Shares issued and outstanding (in shares)		43,700,000		44,500,000
Dividends declared (in dollars per share)					$ 0.2425	$ 0.2425
Maximum shares allowed for issuance (in shares)		2,000,000.0
Par value (in dollars per share)		$ 10
Repurchase shares of Brink's common stock		$ 125,300,000	$ 105,700,000
500 Million Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program amount							$ 500,000,000
Stock repurchased and retired during period (in shares)		1,291,224
Repurchase shares of Brink's common stock		$ 125,300,000
Average price per share (in dollars per share)		$ 97.04
Stock repurchase program remaining amount		$ 375,000,000
250 Million Share Repurchase Program II
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program amount								$ 250,000,000
Stock repurchased and retired during period (in shares)	1,181,106			2,297,955
Repurchase shares of Brink's common stock	$ 88,200,000			$ 169,900,000
Average price per share (in dollars per share)				$ 73.92
Stock repurchase program remaining amount				$ 28,000,000