Pension Plans - Qualified and Non-Qualified Plans - Adjustments to Equity (Details) - Pension Plan [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Change in equity as a result of change in deferred net loss	$ (1.3)	$ 4.5	$ 3.8
Change in equity as result of change in deferred net loss taxes	$ (0.4)	$ 1.5	$ 0.0