Contingencies Enviromental liabilities rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Beginning Balance	$ 16.1
Ending Balance	15.1	$ 16.1
Reserve for Environmental Costs [Member]
Beginning Balance	15.9	16.6
Adjusted to expense (income) during the year	1.2	0.7	$ 0.5
Payments made	2.1	1.4	0.7
Ending Balance	15.0	15.9	16.6
Other operating charges and credits [Member]
Adjusted to expense (income) during the year	0.0	$ 0.0	$ 3.2
Formal cost share [Member]
Other Unrecorded Amounts	2.1
Indemnification Agreement [Member]
Other Unrecorded Amounts	2.1
Other Reserves [Member]
Other Unrecorded Amounts	$ 0.3