Capital Stock (Details) - USD ($)		1 Months Ended	12 Months Ended
	Aug. 26, 2020	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 21, 2021	Feb. 06, 2020	May 08, 2017
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)			49,500,000	50,100,000
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			$ 50,000,000.0	$ 0	$ 93,500,000
250 Million Share Repurchase Program
Subsequent Event [Line Items]
Stock repurchase program amount							$ 250,000,000
200 Million Share Repurchase Program
Subsequent Event [Line Items]
Stock repurchase program amount								$ 200,000,000
Stock repurchased and retired during period, shares			1,300,000
Repurchase shares of Brink's common stock			$ 94,000,000
Average price per share (in dollars per share)				$ 69.35
Stock repurchase program remaining amount			$ 106,000,000
Subsequent Event
Subsequent Event [Line Items]
Dividend declared (in dollars per share)						$ 0.15
ASR August 2020
Subsequent Event [Line Items]
Stock repurchased and retired during period, shares	849,978
Accelerated share repurchases payment	$ 50,000,000
ASR, initial price per share (in dollars per share)	$ 58.83
ASR September 2020
Subsequent Event [Line Items]
Stock repurchased and retired during period, shares		246,676
ASR, final price per share (in dollars per share)		$ 45.59