Consolidated Statement of Equity - USD ($) shares in Millions, $ in Millions		Total	Cumulative Effect, Period of Adoption, Adjustment		Common Stock	Capital in Excess of Par Value	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment		AOCI*	AOCI* Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interests
Beginning Balance at Dec. 31, 2018		$ 166.6	$ 0.0		$ 49.7	$ 628.2	$ 429.1	$ 28.8		$ (953.3)	$ (28.8)	$ 12.9
Beginning Balance (shares) at Dec. 31, 2018					49.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		33.2					29.0					4.2
Other comprehensive income		3.9								3.1		0.8
Stock Repurchased During Period, Value		0.0			$ 0.0	(0.5)	0.5
Stock Repurchased During Period, Shares					0.0
Dividends to:
Brink’s common shareholders ($0.75 per share)		(29.9)					(29.9)
Noncontrolling interests		(2.3)										(2.3)
Stock options and awards:
Compensation expense		42.7				42.7
Other share-based benefit transactions		(6.8)			$ 0.4	(7.1)	(0.1)
Other share-based benefit transactions (shares)					0.4
Capital contributions from noncontrolling interest		0.2										0.2
Ending Balance at Dec. 31, 2019		$ 207.6			$ 50.1	663.3	457.4			(979.0)	(28.8)	15.8
Ending Balance (shares) at Dec. 31, 2019					50.1
Stock options and awards:
Brink's common shareholders per share declared (dollars per share)		$ 0.60
Tax cuts and jobs act, reclassification from AOCI to retained earnings, tax effect	[1]		(1.7)					(1.7)			$ 0.0
Net income		$ 21.9					16.0					5.9
Other comprehensive income		(16.2)								(21.0)		4.8
Stock Repurchased During Period, Value		(50.0)			$ (1.1)	(14.9)	(34.0)
Stock Repurchased During Period, Shares					(1.1)
Brink’s common shareholders ($0.75 per share)		(30.1)					(30.1)
Noncontrolling interests		(16.8)										(16.8)
Compensation expense		31.3				31.3
Other share-based benefit transactions		(7.5)			$ 0.5	(7.9)	(0.1)
Other share-based benefit transactions (shares)					0.5
Acquisitions with noncontrolling interests		64.0										64.0
Ending Balance at Dec. 31, 2020		$ 202.5	$ 0.5	[2]	$ 49.5	671.8	407.5	$ 0.5	[2]	(1,000.0)		73.7
Ending Balance (shares) at Dec. 31, 2020					49.5
Stock options and awards:
Brink's common shareholders per share declared (dollars per share)		$ 0.60
Accounting Standards Update [Extensible Enumeration]		Accounting Standards Update 2016-13
Net income		$ 117.3					105.2					12.1
Other comprehensive income		89.5								92.1		(2.6)
Stock Repurchased During Period, Value		(200.0)			$ (2.4)	(34.6)	(163.0)
Stock Repurchased During Period, Shares					(2.4)
Brink’s common shareholders ($0.75 per share)		(37.2)					(37.2)
Noncontrolling interests		(5.1)										(5.1)
Compensation expense		33.1				33.1
Consideration from exercise of stock options		2.3				2.3
Other share-based benefit transactions		(1.8)			$ 0.3	(2.0)	(0.1)
Other share-based benefit transactions (shares)					0.3
Acquisitions with noncontrolling interests		51.4										51.4
Capital contributions from noncontrolling interest		0.1										0.1
Ending Balance at Dec. 31, 2021		$ 252.6			$ 47.4	$ 670.6	$ 312.9			$ (907.9)		$ 129.6
Ending Balance (shares) at Dec. 31, 2021					47.4
Stock options and awards:
Brink's common shareholders per share declared (dollars per share)		$ 0.75

[1] Effective January 1, 2019, we adopted the provisions of ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. We recognized a cumulative effect adjustment to January 1, 2019 retained earnings as a result of adopting this standard. See Note 1 for further details.

[2] Effective January 1, 2020, we adopted the provisions of ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. We recognized a cumulative effect adjustment to January 1, 2020 retained earnings as a result of adopting this standard. See Note 1 for further details.(c)Effective January 1, 2021, we adopted the provisions of ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. We recognized a cumulative effect adjustment to January 1, 2021 retained earnings as a result of adopting this standard. See Note 1 for further details.