Legal and Environmental Matters Legal and Environmental Matters (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Environmental Remediation Obligations [Abstract]
Beginning balance	$ 12.5	$ 15.7	$ 15.0	$ 15.9
Adjusted to expense	(0.8)	0.8	(1.6)	0.9
Payments made	(0.3)	(1.0)	(2.0)	(1.3)
Ending balance	11.4	$ 15.5	11.4	$ 15.5
Recorded in Other assets	$ 2.0		$ 2.0