Income Taxes Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred income taxes	$ 37.1	$ 367.8
Deferred Tax Liabilities, Net, Noncurrent	(64.6)
Deferred tax assets, net		352.8
Deferred Tax Assets, Net, Noncurrent		352.8
Deferred Tax Liabilities, Net, Noncurrent	101.7	15.0
Deferred Tax Assets, Noncurrent [Member]
Employee benefits	155.9	219.3
Inventory	20.8	20.3
Deferred Tax Assets, Operating Loss Carryforwards	172.4	126.7
Deferred Tax Assets, Tax Credit Carryforwards	96.4	35.1
Deferred Tax Assets, Tax Credit Carryforwards, Other	11.2	11.6
Deferred Tax Assets, Fixed Assets	5.1	15.9
Deferred Tax Assets, Deferred Income	14.7	19.3
Deferred Tax Assets, Noncurrent, Capitalized Expenditures	35.4	71.9
Prepaid taxes and other	26.9	20.5
Deferred Tax Assets, Valuation Allowance, Noncurrent	(180.4)	(164.8)
Deferred income taxes	358.4	375.8
Deferred Tax Liabilities, Noncurrent [Member]
Deferred Tax Liabilities, Undistributed Foreign Earnings	(2.4)	0.0
Deferred Tax Liabilities, Intangible Assets	(281.6)	0.0
Deferred Tax Liabilities, Property, Plant and Equipment	(120.3)	(23.0)
Deferred Tax Liabilities, Other	(18.7)	0.0
Deferred Tax Liabilities, Gross, Noncurrent	423.0	23.0
Foreign [Member]
Deferred Tax Assets, Net, Noncurrent	14.8	11.9
Domestic [Member]
Deferred Tax Assets, Net, Noncurrent		$ 340.9
Deferred Tax Liabilities, Net, Noncurrent	$ 79.4