Business Acquisitions and Dispositions - Summary of Transaction Costs (Details) - Aclara - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Total Aclara Transaction Costs	$ 12.8	$ 7.1
Selling & administrative expense
Business Acquisition [Line Items]
Total Aclara Transaction Costs	9.5	6.7
Interest expense
Business Acquisition [Line Items]
Total Aclara Transaction Costs	$ 3.3	$ 0.4