Segment information - Revenue And Operating Profits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 881.2	$ 872.5	$ 859.0	$ 949.6	$ 997.2	$ 942.1	$ 929.0	$ 910.3	$ 3,562.3	$ 3,778.6	$ 3,577.6
Operating profit	(23.7)	61.2	8.7	(73.7)	59.4	56.9	31.7	15.2	(27.5)	163.2	162.2
Largest 5 Markets [Member]
Segment Reporting Information [Line Items]
Revenues									2,177.2	2,194.8	2,164.2
Operating profit									118.8	135.8	138.6
Global Markets [Member]
Segment Reporting Information [Line Items]
Revenues									1,288.5	1,529.0	1,373.4
Operating profit									166.2	204.2	150.1
Payment Services [Member]
Segment Reporting Information [Line Items]
Revenues									96.6	54.8	40.0
Operating profit									(4.9)	1.0	1.2
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									3,562.3	3,778.6	3,577.6
Operating profit									280.1	341.0	289.9
Reconciling Items [Member] | Selling, General and Administrative Expenses [Member]
Segment Reporting Information [Line Items]
Operating profit									(108.8)	(116.4)	(87.4)
Reconciling Items [Member] | Reconciliation Of Segment Policies To GAAP [Member]
Segment Reporting Information [Line Items]
Operating profit									(2.3)	2.7	4.5
Reconciling Items [Member] | FX devaluation in Venezuela [Member]
Segment Reporting Information [Line Items]
Operating profit									(142.7)	(14.6)	0
Reconciling Items [Member] | US retirement plans [Member]
Segment Reporting Information [Line Items]
Operating profit									(73.1)	(52.9)	(56.2)
Reconciling Items [Member] | 2014 Reorganization and Restructuring [Member]
Segment Reporting Information [Line Items]
Operating profit									(21.8)	0	0
Reconciling Items [Member] | Acquisition and Disposition [Member]
Segment Reporting Information [Line Items]
Operating profit									49.4	5.8	14.6
Reconciling Items [Member] | Mexican settlement losses [Member]
Segment Reporting Information [Line Items]
Operating profit									(5.9)	(2.4)	(3.2)
Reconciling Items [Member] | Share-based compensation adjustment [Member]
Segment Reporting Information [Line Items]
Operating profit									(2.4)	0	0
Latin America [Member] | Global Markets [Member]
Segment Reporting Information [Line Items]
Revenues									592.4	854.2	744.4
Operating profit									90.6	136.2	90.0
Europe, Middle East and Africa [Member] | Global Markets [Member]
Segment Reporting Information [Line Items]
Revenues									556.3	540.6	503.1
Operating profit									52.5	47.0	45.3
Asia Pacific [Member] | Global Markets [Member]
Segment Reporting Information [Line Items]
Revenues									139.8	134.2	125.9
Operating profit									23.1	21.0	14.8
US [Member] | Largest 5 Markets [Member]
Segment Reporting Information [Line Items]
Revenues									727.8	707.5	706.7
Operating profit									22.8	12.8	32.0
France [Member] | Largest 5 Markets [Member]
Segment Reporting Information [Line Items]
Revenues									517.4	517.6	511.4
Operating profit									39.4	44.5	39.7
Mexico [Member] | Largest 5 Markets [Member]
Segment Reporting Information [Line Items]
Revenues									388.2	423.9	395.0
Operating profit									9.6	26.9	17.7
Brazil [Member] | Largest 5 Markets [Member]
Segment Reporting Information [Line Items]
Revenues									364.1	354.4	363.6
Operating profit									34.2	41.1	39.9
Canada [Member] | Largest 5 Markets [Member]
Segment Reporting Information [Line Items]
Revenues									179.7	191.4	187.5
Operating profit									$ 12.8	$ 10.5	$ 9.3