Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Provisional income tax benefit	$ (47.3)
Domestic			$ 96.7	$ 72.9	$ 32.6
Foreign			94.2	97.4	100.0
Income from operations before provision for taxes and equity in earnings			190.9	170.3	132.6
Domestic [Abstract]
Taxes currently payable, Federal			46.0	18.7	1.4
Taxes currently payable, State and local			2.4	4.4	1.2
Deferred income taxes			(78.1)	(8.8)	(3.2)
Domestic tax provision (benefit)			(29.7)	14.3	(0.6)
Foreign [Abstract]
Taxes currently payable			21.1	23.2	22.7
Deferred income taxes			2.0	(2.2)	0.7
Foreign tax provision			23.1	21.0	23.4
Total tax provision (benefit)			$ (6.6)	$ 35.3	$ 22.8
Reconciliation of U. S. federal statutory tax rate to effective tax rate [Abstract]
U.S. statutory rate			35.00%	35.00%	35.00%
Depletion			(6.70%)	(6.60%)	(8.40%)
Difference between tax provided on foreign earnings and the US statutory rate			(3.80%)	(6.40%)	(8.30%)
State and local taxes, net of federal tax benefit			1.10%	1.10%	0.30%
Tax credits and foreign dividends			0.30%	0.60%	(0.50%)
Change in valuation allowance			(1.90%)	(1.10%)	(0.90%)
Impact of uncertain tax positions			0.40%	0.40%	(0.10%)
Impact of officer's non-deductible compensation			0.80%	0.10%	2.90%
Manufacturing deduction			(1.60%)	(2.00%)	(2.00%)
Impact of US Tax Reform			(24.80%)	(0.00%)	(0.00%)
Other			(2.30%)	(0.40%)	(0.80%)
Consolidated effective tax rate			(3.50%)	20.70%	17.20%
Deferred tax assets attributable to [Abstract]
Accrued liabilities	28.6		$ 28.6	$ 49.7
Net operating loss carry forwards	33.2		33.2	34.6
Pension and post-retirement benefits costs	40.4		40.4	55.4
Other	22.0		22.0	35.0
Valuation allowance	(21.4)		(21.4)	(24.8)
Total deferred tax assets	102.8		102.8	149.9
Deferred tax liabilities attributable to [Abstract]
Plant and equipment, principally due to differences in depreciation	161.6		161.6	251.3
Intangible assets	63.4		63.4	96.3
Other	11.6		11.6	14.0
Total deferred tax liabilities	236.6		236.6	361.6
Net deferred tax asset (liability)	(133.8)		(133.8)	(211.7)
Current and long-term portion of net deferred tax assets [Abstract]
Net deferred tax asset, long-term	25.6		25.6	27.1
Net deferred tax liability, long-term	159.4		159.4	238.8
Net deferred tax asset (liability), long-term	(133.8)		(133.8)	(211.7)
Operating Loss Carryforwards [Line Items]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	33.2		$ 33.2
Expiration period			20 years
Unrecognized tax benefits [Abstract]
Unrecognized tax benefits that would impact effective tax rate	11.9		$ 11.9
Unrecognized tax benefits [Roll forward]
Balance at beginning of the year		$ 14.7	13.7	4.0
Increases related to current year positions			1.2	8.8
Increases related to new judgments			1.2	0.9
Decreases related to audit settlements and statute expirations			(1.4)	0.0
Balance at the end of the year	14.7		14.7	13.7	$ 4.0
Income Tax Penalties and Interest Expense [Abstract]
Unrecognized tax benefits, net reversal of accrued interest and penalties			0.4
Unrecognized tax benefits, accrued interest and penalties	1.7		1.7
Cash paid for income taxes [Abstract]
Net cash Income taxes paid			47.7	$ 30.6	$ 43.8
Undistributed earnings of foreign subsidiaries [Abstract]
Foreign subsidiaries' undistributed earnings	531.2		531.2
Deferred tax liabilities with respect to foreign withholding taxes or state taxes have been recognized	0.0		0.0
Finite lived tax loss carry forwards [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	15.5		15.5
Indefinite lived tax loss carry forwards [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	$ 17.7		$ 17.7
Plan [Member]
Reconciliation of U. S. federal statutory tax rate to effective tax rate [Abstract]
U.S. statutory rate		21.00%