Income Taxes - Valuation Allowances (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Valuation Allowances [Roll Forward]
Beginning of year				$ 45.9				$ 45.4	$ 45.9	$ 45.4	$ 183.6
Expiring tax credits									(0.3)	(0.6)	(0.7)
Acquisitions and dispositions									0.3	(10.0)	0.3
Changes in judgment about deferred tax assets									(8.2)	(0.9)	(119.8)
Valuation and Qualifying Accounts Disclosure [Line Items]
Amounts attributable to Brink's Income (loss) from Continuing operations	17.3	31.5	5.3	18.9	19.2	21.7	20.7	(4.8)	73.0	56.8	195.7
Income (loss) from discontinued operations	(1.5)	(0.7)	2.6	1.1	0.7	2.2	0.8	(3.4)	1.5	0.3	4.5
Other Comprehensive Income (Loss), Net of Tax									(179.6)	(26.7)	(3.3)
Foreign currency exchange effects									(1.4)	(1.9)	1.5
End of year	43.9				45.9				43.9	45.9	45.4
Valuation Allowance Related to Federal and State											117.8
Valuation Allowance Reversal											25.4
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Amounts attributable to Brink's Income (loss) from Continuing operations									7.6	14.9	7.1
Income (loss) from discontinued operations									0	(1.1)	1.7
Other Comprehensive Income (Loss), Net of Tax									$ 0	$ 0.1	$ (28.3)