Capital Stock (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	May 01, 2024	Jan. 18, 2024	Nov. 02, 2023	Oct. 27, 2021
Subsequent Event [Line Items]
Shares of common stock authorized (in shares)	100,000,000.0		100,000,000.0
Shares issued and outstanding (in shares)	44,600,000		44,500,000
Dividends declared (in dollars per share)					$ 0.22
Maximum shares allowed for issuance (in shares)	2,000,000
Par value (in dollars per share)	$ 10
Repurchase shares of Brink's common stock	$ 23,000,000.0	$ 16,000,000.0
Subsequent Event
Subsequent Event [Line Items]
Dividends declared (in dollars per share)				$ 0.2425
500 Million Share Repurchase Program
Subsequent Event [Line Items]
Stock repurchase program amount						$ 500,000,000
Stock repurchased and retired during period (in shares)	274,680
Repurchase shares of Brink's common stock	$ 23,000,000
Average price per share (in dollars per share)	$ 83.77
Stock repurchase program remaining amount	$ 477,000,000
250 Million Share Repurchase Program II
Subsequent Event [Line Items]
Stock repurchase program amount							$ 250,000,000
Stock repurchased and retired during period (in shares)			2,297,955
Repurchase shares of Brink's common stock			$ 169,900,000
Average price per share (in dollars per share)			$ 73.92
Stock repurchase program remaining amount			$ 28,000,000