Basis of presentation (Details) $ in Millions	3 Months Ended					12 Months Ended
	Mar. 31, 2019 USD ($) segment $ / $		Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($) $ / $		Dec. 31, 2018 USD ($) $ / $	Jan. 01, 2019 USD ($)	Dec. 31, 2017 USD ($) $ / $
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating segments | segment	3
Net monetary assets	$ 1,154.3					$ 1,206.5
Cash and cash equivalents	283.2					343.4
Goodwill	751.7					678.6
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Deconsolidation, pretax	(8.7)			$ (15.0)
Cumulative effect of change in accounting principle	0.0	[1]		$ 2.2	[2]
Right-of-use assets, net	$ 292.2					$ 0.0
Argentine pesos | Argentina
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percent of Consolidated Revenue	6.00%			8.00%
Rate decrease percent	13.00%			8.00%		50.00%
Official exchange rate | $ / $	43.3			20.2		37.6		18.6
Net remeasurement loss	$ (3.9)					$ (6.2)
Net monetary assets	28.4
Cash and cash equivalents	17.2
Nonmonetary assets	149.7
Goodwill	99.8
Equity Securities	0.0
Venezuelan bolívar fuerte | Venezuela
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Rate decrease percent			97.00%
Net remeasurement loss				$ 2.8
Loss on deconsolidation of Venezuela operations			$ 127.0
Derecognition of the carrying amounts of assets included in the deconsolidation charge			32.0
Derecognition of the carrying amounts of liabilities included in the deconsolidation charge			11.0
Income (loss) attributable to noncontrolling interest				2.0
Foreign currency translation adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Deconsolidation, pretax	0.0			0.0
Foreign currency translation adjustments | Venezuelan bolívar fuerte | Venezuela
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Deconsolidation, pretax			$ 106.0
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle	$ 28.8	[1]		$ 3.3	[2]
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

[1] Effective January 1, 2019, we adopted the provisions of ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. We recognized a cumulative effect adjustment to January 1, 2019 retained earnings as a result of adopting this standard. See Note 1 for further details.

[2] 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.