Segment information - Assets, Long Lived Assets, Revenues, Net Assets by Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Assets held by Reportable Segment	$ 3,763.8				$ 3,236.0				$ 3,763.8	$ 3,236.0	$ 3,059.6
Long-Lived Assets by Geographic Area	763.3				699.4				763.3	699.4	640.9
Revenues	935.8	$ 928.4	$ 914.0	$ 905.0	907.7	$ 852.4	$ 849.7	$ 879.1	3,683.2	3,488.9	3,347.0
Net assets outside the U.S.	1,260.1				1,141.5				1,260.1	1,141.5	1,191.0
Reportable Segments:
Segment Reporting Information [Line Items]
Assets held by Reportable Segment	3,495.9				2,947.7				3,495.9	2,947.7	2,357.3
Revenues									3,679.7	3,437.5	3,192.9
Corporate items
Segment Reporting Information [Line Items]
Assets held by Reportable Segment	267.9				288.3				267.9	288.3	643.6
North America | Reportable Segments:
Segment Reporting Information [Line Items]
Assets held by Reportable Segment	1,683.0				1,404.5				1,683.0	1,404.5	733.5
Revenues									1,782.8	1,466.3	1,254.2
South America | Reportable Segments:
Segment Reporting Information [Line Items]
Assets held by Reportable Segment	806.1				602.5				806.1	602.5	740.5
Revenues									916.5	926.9	924.6
Rest of World | Reportable Segments:
Segment Reporting Information [Line Items]
Assets held by Reportable Segment	1,006.8				940.7				1,006.8	940.7	883.3
Revenues									980.4	1,044.3	1,014.1
Mexico
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	129.4				107.0				129.4	107.0	99.6
Revenues									412.4	365.3	327.2
Net assets outside the U.S.	181.3				154.8				181.3	154.8	133.7
France
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	74.1				79.0				74.1	79.0	84.1
Revenues									373.2	428.5	429.4
Net assets outside the U.S.	155.4				213.4				155.4	213.4	219.4
Brazil
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	72.2				62.5				72.2	62.5	57.2
Revenues									440.4	405.4	434.6
Net assets outside the U.S.	274.1				147.9				274.1	147.9	151.3
ARGENTINA
Segment Reporting Information [Line Items]
Revenues									214.4	247.2	250.3
Net assets outside the U.S.	166.1				154.6				166.1	154.6	234.0
Venezuela
Segment Reporting Information [Line Items]
Revenues									0.0	51.4	154.1
Venezuela | Other items not allocated to segments:
Segment Reporting Information [Line Items]
Assets held by Reportable Segment	0.0				0.0				0.0	0.0	58.7
Revenues									0.0	51.4	154.1
Canada
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	54.1				47.6				54.1	47.6	46.7
Revenues									149.8	151.7	151.2
Net assets outside the U.S.	45.9				52.0				45.9	52.0	63.3
Other
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	150.0				135.4				150.0	135.4	146.5
Revenues									868.4	890.1	824.4
Subtotal
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	479.8				431.5				479.8	431.5	434.1
Revenues									2,458.6	2,539.6	2,571.2
U.S.
Segment Reporting Information [Line Items]
Long-Lived Assets by Geographic Area	283.5				267.9				283.5	267.9	206.8
Revenues									1,224.6	949.3	775.8
Other Rest of World countries
Segment Reporting Information [Line Items]
Net assets outside the U.S.	313.6				309.2				313.6	309.2	273.1
Other South American countries
Segment Reporting Information [Line Items]
Net assets outside the U.S.	$ 123.7				$ 109.6				$ 123.7	$ 109.6	$ 116.2