Segment information - Capital Expenditures, Depreciation, Amortization (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Capital Expenditures by Reportable Segment	$ 57.1	$ 46.3	$ 43.3	$ 27.8	$ 39.8	$ 27.4	$ 24.2	$ 20.8	$ 174.5	$ 112.2	$ 101.1
Depreciation and Amortization by Reportable Segment									138.2	128.0	135.7
Amortization of intangible assets:									8.4	3.6	4.2
Total	$ 40.2	$ 37.9	$ 34.6	$ 33.9	$ 34.1	$ 32.4	$ 32.9	$ 32.2	146.6	131.6	139.9
Reportable Segments:
Segment Reporting Information [Line Items]
Capital Expenditures by Reportable Segment									161.4	98.2	89.8
Depreciation and Amortization by Reportable Segment									122.3	115.6	120.5
Reportable Segments: | North America
Segment Reporting Information [Line Items]
Capital Expenditures by Reportable Segment									86.3	42.0	37.1
Depreciation and Amortization by Reportable Segment									68.4	66.8	70.1
Reportable Segments: | South America
Segment Reporting Information [Line Items]
Capital Expenditures by Reportable Segment									39.2	24.0	21.4
Depreciation and Amortization by Reportable Segment									23.5	19.0	19.5
Reportable Segments: | Rest of World
Segment Reporting Information [Line Items]
Capital Expenditures by Reportable Segment									35.9	32.2	31.3
Depreciation and Amortization by Reportable Segment									30.4	29.8	30.9
Corporate items
Segment Reporting Information [Line Items]
Capital Expenditures by Reportable Segment									8.9	9.0	7.0
Depreciation and Amortization by Reportable Segment									12.0	10.9	11.3
Venezuela | Other items not allocated to segments:
Segment Reporting Information [Line Items]
Capital Expenditures by Reportable Segment									4.2	5.0	4.3
Depreciation and Amortization by Reportable Segment									1.7	0.7	3.9
Reorganization and Restructuring | Other items not allocated to segments:
Segment Reporting Information [Line Items]
Depreciation and Amortization by Reportable Segment									$ 2.2	$ 0.8	$ 0.0