Basis of presentation (Details) $ in Millions	3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($) $ / $	Sep. 30, 2018 USD ($) $ / $	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) $ / $	Sep. 30, 2019 USD ($) segment $ / $	Sep. 30, 2018 USD ($) $ / $	Dec. 31, 2017 USD ($) $ / $	Mar. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)	Mar. 31, 2018 USD ($)	[1]	Jan. 01, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating segments | segment					3
Net monetary assets	$ 1,246.1			$ 1,206.5	$ 1,246.1
Cash and cash equivalents	337.0			343.4	337.0
Goodwill	776.0			678.6	776.0
Loss on deconsolidation of Venezuela operations	0.0	$ 0.0			0.0	$ (126.7)
Revenues	928.4	$ 852.4			2,747.4	$ 2,581.2
Cumulative effect of change in accounting principle								$ 0.0		$ 2.2
Right-of-use assets, net	$ 269.3			$ 0.0	$ 269.3
Argentine pesos | Argentina
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percent of Consolidated Revenue					6.00%	8.00%
Rate decrease percent	35.00%	55.00%		50.00%	35.00%	55.00%
Official exchange rate | $ / $	57.5	41.3		37.6	57.5	41.3	18.6
Net remeasurement loss				$ (6.2)	$ (10.4)
Net monetary assets	$ 25.5				25.5
Cash and cash equivalents	16.6				16.6
Nonmonetary assets	151.0				151.0
Goodwill	99.8				99.8
Equity Securities	0.0				0.0
Venezuelan bolívar fuerte | Venezuela
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss on deconsolidation of Venezuela operations			$ 127.0
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle								$ 28.8		$ 3.3
Accounting Standards Update 2014-09 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle												$ 1.5
Accounting Standards Update 2016-01 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle												1.1
Accounting Standards Update 2016-16 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle												$ 0.7
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets, net									$ 310.1
Lease liabilities									320.3
Accounting Standards Update 2018-02 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle									$ 28.8
Internal Loss AR Rebuild
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Third-party expense					$ 3.9
Revenues	4.0
Bank fees	0.3
Increase to bad debt expense	13.7						$ 12.6
Accounts receivable							$ 25.3
Immaterial error correction	$ 10.0

[1] Effective January 1, 2018, we adopted the provisions of ASU 2014-09, Revenue From Contracts with Customers, ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, and ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory. We recognized a cumulative effect adjustment to January 1, 2018 retained earnings as a result of adopting each of these standards. See Note 1 for further details of the impact of each standard.