Condensed Consolidated Statement of Equity (Unaudited) - 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		Accumulated Other Comprehensive Loss	Noncontrolling Interests
Beginning balance at Dec. 31, 2019		$ 207.6	$ (1.7)	[1]	$ 50.1	$ 663.3	$ 457.4	$ (1.7)	[1]	$ (979.0)	$ 15.8
Beginning balance, Shares at Dec. 31, 2019					50.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update	[1]	Accounting Standards Update 2016-13
Net income		$ 2.8					1.8				1.0
Other comprehensive loss		(117.4)								(117.0)	(0.4)
Dividends to:
Brink’s common shareholders		(7.5)					(7.5)
Noncontrolling interests		(0.7)									(0.7)
Stock options and awards
Compensation expense		7.2				7.2
Other share-based benefit transactions		(8.3)			$ 0.4	(8.6)	(0.1)
Other share-based benefit transactions, shares					0.4
Ending balance at Mar. 31, 2020		$ 82.0			$ 50.5	661.9	449.9			(1,096.0)	15.7
Ending balance, Shares at Mar. 31, 2020					50.5
Stock options and awards
Dividends (dollars per share)		$ 0.15
Beginning balance at Dec. 31, 2019		$ 207.6	(1.7)	[1]	$ 50.1	663.3	457.4	(1.7)	[1]	(979.0)	15.8
Beginning balance, Shares at Dec. 31, 2019					50.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		(4.5)
Other comprehensive loss		(27.5)								(30.1)
Ending balance at Sep. 30, 2020		171.9			$ 49.4	660.0	389.7			(1,009.1)	81.9
Ending balance, Shares at Sep. 30, 2020					49.4
Beginning balance at Mar. 31, 2020		82.0			$ 50.5	661.9	449.9			(1,096.0)	15.7
Beginning balance, Shares at Mar. 31, 2020					50.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		15.2					12.9				2.3
Other comprehensive loss		35.2								34.2	1.0
Dividends to:
Brink’s common shareholders		(7.6)					(7.6)
Noncontrolling interests		(7.2)									(7.2)
Stock options and awards
Compensation expense		5.4				5.4
Other share-based benefit transactions		0.1			$ 0.0	0.1
Other share-based benefit transactions, shares					0.0
Acquisitions with noncontrolling interests		67.8									67.8
Ending balance at Jun. 30, 2020		$ 190.9			$ 50.5	667.4	455.2			(1,061.8)	79.6
Ending balance, Shares at Jun. 30, 2020					50.5
Stock options and awards
Dividends (dollars per share)		$ 0.15
Net income		$ (22.5)					(23.9)				1.4
Other comprehensive loss		54.7								52.7	2.0
Shares repurchased		(50.0)			$ (1.1)	(14.9)	(34.0)
Shares repurchased, shares					(1.1)
Brink’s common shareholders		(7.6)					(7.6)
Noncontrolling interests		(1.0)									(1.0)
Compensation expense		8.3				8.3
Other share-based benefit transactions		(0.8)				(0.8)
Acquisitions with noncontrolling interests		0.1									0.1
Ending balance at Sep. 30, 2020		$ 171.9			$ 49.4	660.0	389.7			(1,009.1)	81.9
Ending balance, Shares at Sep. 30, 2020					49.4
Stock options and awards
Dividends (dollars per share)		$ 0.15
Beginning balance at Dec. 31, 2020		$ 202.5	0.5	[2]	$ 49.5	671.8	407.5	0.5	[2]	(1,000.0)	73.7
Beginning balance, Shares at Dec. 31, 2020					49.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update	[2]	Accounting Standards Update 2019-12
Net income		$ 15.4					12.7				2.7
Other comprehensive loss		(42.8)								(40.7)	(2.1)
Dividends to:
Brink’s common shareholders		(7.4)					(7.4)
Noncontrolling interests		(0.4)									(0.4)
Stock options and awards
Compensation expense		7.6				7.6
Consideration from exercise of stock options		2.3				2.3
Other share-based benefit transactions		(4.0)			$ 0.2	(4.2)
Other share-based benefit transactions, shares					0.2
Acquisitions with noncontrolling interests		51.4									51.4
Ending balance at Mar. 31, 2021		$ 225.1			$ 49.7	677.5	413.3			(1,040.7)	125.3
Ending balance, Shares at Mar. 31, 2021					49.7
Stock options and awards
Dividends (dollars per share)		$ 0.15
Beginning balance at Dec. 31, 2020		$ 202.5	$ 0.5	[2]	$ 49.5	671.8	407.5	$ 0.5	[2]	(1,000.0)	73.7
Beginning balance, Shares at Dec. 31, 2020					49.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		65.3
Other comprehensive loss		(17.7)								(14.6)
Ending balance at Sep. 30, 2021		249.0			$ 49.1	690.7	396.2			(1,014.6)	127.6
Ending balance, Shares at Sep. 30, 2021					49.1
Beginning balance at Mar. 31, 2021		225.1			$ 49.7	677.5	413.3			(1,040.7)	125.3
Beginning balance, Shares at Mar. 31, 2021					49.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		26.9					23.9				3.0
Other comprehensive loss		49.5								49.2	0.3
Dividends to:
Brink’s common shareholders		(10.0)					(10.0)
Noncontrolling interests		(1.1)									(1.1)
Stock options and awards
Compensation expense		11.1				11.1
Other share-based benefit transactions		0.0			$ 0.1	(0.1)
Other share-based benefit transactions, shares					0.1
Acquisitions with noncontrolling interests		1.1									1.1
Ending balance at Jun. 30, 2021		$ 302.6			$ 49.8	688.5	427.2			(991.5)	128.6
Ending balance, Shares at Jun. 30, 2021					49.8
Stock options and awards
Dividends (dollars per share)		$ 0.20
Net income		$ 23.0					19.0				4.0
Other comprehensive loss		(24.4)								(23.1)	(1.3)
Shares repurchased		(50.0)			$ (0.7)	(9.3)	(40.0)
Shares repurchased, shares					(0.7)
Brink’s common shareholders		(9.9)					(9.9)
Noncontrolling interests		(3.5)									(3.5)
Compensation expense		9.2				9.2
Other share-based benefit transactions		2.2			$ 0.0	2.3	(0.1)
Other share-based benefit transactions, shares					0.0
Capital contributions from noncontrolling interest		0.1									0.1
Acquisitions with noncontrolling interests		0.3									0.3
Ending balance at Sep. 30, 2021		$ 249.0			$ 49.1	$ 690.7	$ 396.2			$ (1,014.6)	$ 127.6
Ending balance, Shares at Sep. 30, 2021					49.1
Stock options and awards
Dividends (dollars per share)		$ 0.20

[1] 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.

[2] 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.