Restructuring - 2014 Restructuring (Details) - Restructuring Plan 2014 - USD ($) $ in Millions	12 Months Ended			39 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Estimated effect on future earnings	$ 10.8
Restructuring charges, incurred				$ 60.6
Restructuring charges net of tax	0.2	$ (0.2)	$ 11.0	45.0
Utilized non-cash				48.3
Cash				12.3
Infrastructure Solutions
Restructuring Cost and Reserve [Line Items]
Estimated effect on future earnings	8.4
Infrastructure Solutions | Non-Cash Restructuring
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	26.1			26.1
Corrosion Protection
Restructuring Cost and Reserve [Line Items]
Estimated effect on future earnings	2.4
Corrosion Protection | Non-Cash Restructuring
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	$ 22.2			$ 22.2