Income tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Benefit on Goodwill Impairment		$ 51.1
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		77.8
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal		68.1	$ 63.2	$ 71.8
Foreign		16.2	20.1	28.0
State and local		5.6	5.2	8.0
Total current tax expense		89.9	88.5	107.8
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Total deferred tax expense		(131.2)	26.2	14.2
Provision for income taxes		(41.3)	114.7	122.0
Net deferred tax liabilities		102.0	216.2
Effect of Tax Cuts and Jobs Act of 2017, Repatriation Transition Tax		10.6
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense		1.1	1.2	1.5
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest [Abstract]
U.S. income before income taxes		210.9	283.6	260.1
Non-U.S. income before income taxes		(158.2)	67.3	103.8
Income from continuing operations before income taxes		52.7	350.9	363.9
Components of Deferred Tax Assets [Abstract]
Accounts receivable, principally due to allowances for returns and doubtful accounts		2.9	4.1
Inventories, principally due to additional costs inventories for tax purposes		17.7	22.9
Employee compensation and benefits accrued for financial reporting purposes		36.5	60.6
Foreign net operating losses		24.5	25.7
Foreign tax credits		34.1	24.1
Other		16.1	12.8
Total deferred tax assets		131.8	150.2
Less valuation allowance		(48.5)	(40.3)
Total deferred tax assets after valuation allowance		83.3	109.9
Components of Deferred Tax Liabilities [Abstract]
Plant and equipment, principally due to differences in depreciation, capitalized interest, and capitalized overhead		86.4	130.9
Goodwill and intangible assets, principally due to differences in amortization		98.9	195.2
Total deferred tax liabilities		185.3	326.1
Deferred tax liabilities, net		102.0	216.2
Deferred Tax Assets, Net, Classification [Abstract]
Deferred tax liabilities		153.5	219.7
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed expected tax expense on income before taxes at federal statutory rate		18.5	122.8	127.4
Increase (Decrease) Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
State and local income taxes net of federal income tax benefit		3.3	5.6	5.6
Foreign tax rate differential		(4.7)	(7.4)	(7.5)
Manufacturing tax benefits		(6.0)	(5.8)	(6.7)
Other		(2.0)	(0.5)	3.2
Actual income tax expense		$ (41.3)	$ 114.7	$ 122.0
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal statutory rate	21.00%	35.00%	35.00%	35.00%
Increase (Decrease) Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
State and local income taxes net of federal income tax benefit		6.20%	1.60%	1.50%
Foreign tax rate differential		(8.90%)	(2.10%)	(2.10%)
Manufacturing tax benefits		(11.30%)	(1.70%)	(1.80%)
Other		(3.80%)	(0.10%)	0.90%
Effective tax rate		(78.40%)	32.70%	33.50%
Effective Income Tax Rate Reconciliation, Goodwill Impairment Rate Differential, Amount		$ 17.7	$ 0.0	$ 0.0
Effective Income Tax Rate Reconciliation, Goodwill Impairment Rate Differential, Percent		33.60%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Effect of Tax Cuts and Jobs Act of 2017, Amount		$ (67.2)	$ 0.0	$ 0.0
Effective Income Tax Rate Reconciliation, Effect of Tax Cuts and Jobs Act of 2017, Percent		(127.50%)	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount		$ (0.9)	$ 0.0	$ 0.0
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent		(1.70%)	0.00%	0.00%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 35.2	$ 32.9	$ 30.7
Additions based on tax positions related to the current year		3.9	2.3
Additions for tax positions of prior years		4.1	7.0
Reductions for tax positions of prior years		(1.1)	(4.5)
Reductions due to a lapse of the statute of limitations		(4.5)	(1.7)
Settlements		(0.1)	(0.9)
Balance at end of year		35.2	32.9	$ 30.7
Operating loss carryforwards		88.5
Operating loss carryforwards subject to expiration		23.0
Foreign tax credit carryforward		34.1
Valuation allowance		48.5	40.3
Undistributed foreign subsidiaries earnings		255.8
Unrecognized tax benefits that would impact effective tax rate		35.2	32.9
Interest and penalties		14.5	13.2
Unrecognized Tax Benefits, Increase Resulting from Acquisition			2.6
Interest and penalties resulting from acquisitions			2.5
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit		10.0
Continuing Operations [Member]
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal		(73.2)	26.7	11.5
Foreign		(58.5)	(3.9)	2.1
State and local		0.5	3.4	0.6
Total deferred tax expense		(131.2)	26.2	$ 14.2
Deferred charges and other assets [Member]
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Net deferred tax liabilities		51.5	3.5
Components of Deferred Tax Liabilities [Abstract]
Deferred tax liabilities, net		$ 51.5	$ 3.5