Segment information - Revenue And Operating Profits (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 765.8	$ 759.2	$ 760.3	$ 776.1	$ 881.2	$ 872.5	$ 859.0	$ 949.6	$ 3,061.4	$ 3,562.3	$ 3,778.6
Operating Profit (Loss)	$ 33.0	$ 25.3	$ (14.6)	12.9	$ (23.7)	$ 61.2	$ 8.7	(73.7)	56.6	(27.5)	163.2
Foreign currency transaction losses				$ (18.0)				$ (121.9)	(26.8)	(127.2)	(18.1)
Share-based compensation adj.									0.8	(136.9)	327.7
Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									2,976.9	3,350.5	3,331.5
Operating Profit (Loss)									242.0	239.9	264.4
Corporate items:
Segment Reporting Information [Line Items]
General, administrative and other expenses									(81.0)	(110.8)	(117.7)
Foreign currency transaction losses									(8.8)	(2.6)	(2.4)
Reconciliation of segment policies to GAAP									4.6	(2.3)	2.7
Other items not allocated to segments:
Segment Reporting Information [Line Items]
Reorganization and Restructuring									(15.3)	(21.8)	0.0
U.S. and Mexican retirement plans									(31.2)	(79.0)	(55.3)
Acquisitions and dispositions									(6.0)	49.4	5.8
Share-based compensation adj.									0.0	(2.4)	0.0
Largest 5 Markets | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									1,919.0	2,177.2	2,194.8
Operating Profit (Loss)									108.5	118.8	135.8
Global Markets | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									972.0	1,076.7	1,081.9
Operating Profit (Loss)									140.7	126.0	127.6
Venezuela
Segment Reporting Information [Line Items]
Foreign currency transaction losses									(18.1)
Venezuela | Other items not allocated to segments:
Segment Reporting Information [Line Items]
Revenues									84.5	211.8	447.1
Operating Profit (Loss)									(47.7)	(97.9)	65.7
U.S. | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									730.4	727.8	707.5
Operating Profit (Loss)									15.1	22.8	12.8
France | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									431.5	517.4	517.6
Operating Profit (Loss)									34.7	39.4	44.5
Mexico | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									333.0	388.2	423.9
Operating Profit (Loss)									24.2	9.6	26.9
Brazil | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									270.4	364.1	354.4
Operating Profit (Loss)									23.8	34.2	41.1
Canada | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									153.7	179.7	191.4
Operating Profit (Loss)									10.7	12.8	10.5
Latin America | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									369.9	380.6	407.1
Operating Profit (Loss)									76.3	50.4	59.6
EMEA | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									444.7	556.3	540.6
Operating Profit (Loss)									35.7	52.5	47.0
Asia | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									157.4	139.8	134.2
Operating Profit (Loss)									28.7	23.1	21.0
Payment Services | Reportable Segments:
Segment Reporting Information [Line Items]
Revenues									85.9	96.6	54.8
Operating Profit (Loss)									$ (7.2)	$ (4.9)	$ 1.0