Segment information - Assets, Long Lived Assets, Revenues, Net Assets by Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Assets held by Segment	$ 1,994.8				$ 1,946.7				$ 1,994.8	$ 1,946.7	$ 2,192.0
Long-Lived Assets by Geographic Area	531.0				549.0				531.0	549.0	669.5
Revenues by Geographic Area	803.5	$ 755.8	$ 739.5	$ 721.8	765.8	$ 759.2	$ 760.3	$ 776.1	3,020.6	3,061.4	3,562.3
Net assets outside the U.S.	684.1				647.8				684.1	647.8	746.9
Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	1,622.6				1,567.4				1,622.6	1,567.4	1,759.0
Revenues by Geographic Area									2,908.4	2,976.9	3,350.5
Corporate items
Segment Reporting Information [Line Items]
Assets held by Segment	321.3				332.4				321.3	332.4	326.8
U.S. | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	338.0				325.0				338.0	325.0	327.4
Revenues by Geographic Area									752.6	730.4	727.8
France | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	286.7				239.6				286.7	239.6	244.7
Revenues by Geographic Area									424.5	431.5	517.4
Mexico | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	201.4				229.0				201.4	229.0	258.9
Revenues by Geographic Area									295.3	333.0	388.2
Brazil | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	145.6				109.7				145.6	109.7	165.0
Revenues by Geographic Area									285.7	270.4	364.1
Canada | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	87.0				81.3				87.0	81.3	92.3
Revenues by Geographic Area									150.2	153.7	179.7
Latin America | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	172.8				155.3				172.8	155.3	189.8
Revenues by Geographic Area									355.1	369.9	380.6
EMEA | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	238.9				274.6				238.9	274.6	308.0
Revenues by Geographic Area									387.4	444.7	556.3
Asia | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	96.2				99.8				96.2	99.8	109.2
Revenues by Geographic Area									167.5	157.4	139.8
Payment Services | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	56.0				53.1				56.0	53.1	63.7
Revenues by Geographic Area									90.1	85.9	96.6
Largest 5 Markets | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	1,058.7				984.6				1,058.7	984.6	1,088.3
Revenues by Geographic Area									1,908.3	1,919.0	2,177.2
France
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	67.5				68.1				67.5	68.1	75.7
Revenues by Geographic Area									424.5	431.5	517.4
Net assets outside the U.S.	102.1				87.1				102.1	87.1	96.3
Mexico
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	78.1				93.2				78.1	93.2	114.4
Revenues by Geographic Area									296.3	333.7	388.5
Net assets outside the U.S.	86.1				86.1				86.1	86.1	88.4
Brazil
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	45.3				34.0				45.3	34.0	47.9
Revenues by Geographic Area									344.9	336.4	442.3
Net assets outside the U.S.	106.3				87.9				106.3	87.9	111.1
Canada
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	42.4				38.9				42.4	38.9	47.9
Revenues by Geographic Area									150.2	153.7	179.7
Net assets outside the U.S.	57.6				50.3				57.6	50.3	53.4
Other
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	127.2				122.7				127.2	122.7	175.5
Revenues by Geographic Area									1,040.9	1,069.6	1,305.8
Global Markets | Business segments
Segment Reporting Information [Line Items]
Assets held by Segment	507.9				529.7				507.9	529.7	607.0
Revenues by Geographic Area									910.0	972.0	1,076.7
Venezuela
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	10.1								10.1
Venezuela | Reconciling items
Segment Reporting Information [Line Items]
Assets held by Segment	50.9				46.9				50.9	46.9	106.2
Revenues by Geographic Area									109.4	84.5	211.8
Subtotal
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	360.5				356.9				360.5	356.9	461.4
Revenues by Geographic Area									2,256.8	2,324.9	2,833.7
U.S.
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	170.5				192.1				170.5	192.1	208.1
Revenues by Geographic Area									763.8	736.5	728.6
Other EMEA countries
Segment Reporting Information [Line Items]
Net assets outside the U.S.	133.8				147.5				133.8	147.5	146.1
Other Latin American countries
Segment Reporting Information [Line Items]
Net assets outside the U.S.	127.0				115.2				127.0	115.2	182.4
Asian countries
Segment Reporting Information [Line Items]
Net assets outside the U.S.	$ 71.2				$ 73.7				$ 71.2	$ 73.7	$ 69.2