Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Cash Flow Statements, Captions [Line Items]
Interest		$ 27.1	$ 20.1	$ 18.6
Income taxes, net		83.8	64.3	45.4
Transaction proceeds		0.0	0.0	14.5
Capital leases	$ 51.7	51.7	29.4	18.9
Payment of acquisition-related obligation	90.9	90.9	0.0	0.0
Restricted cash	112.6	112.6	55.5
Argentina, Pesos
Condensed Cash Flow Statements, Captions [Line Items]
Purchase of debt securities		37.1	2.1	25.8
Proceeds from sale of securities		$ 36.9	2.0	$ 18.7
Mexico City | Brink's Mexico
Condensed Cash Flow Statements, Captions [Line Items]
Lease term (in years)		2 years		2 years
Transaction proceeds				$ 14.5
Cash from Short Term Borrowings
Condensed Cash Flow Statements, Captions [Line Items]
Restricted cash	27.0	$ 27.0	22.3
Cash Held From Customers
Condensed Cash Flow Statements, Captions [Line Items]
Restricted cash	74.7	74.7	$ 33.2
Deposits Liability
Condensed Cash Flow Statements, Captions [Line Items]
Restricted cash	$ 10.9	$ 10.9