Pension and Other Post-Retirement Benefits - Projected and Accumulated Benefit Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract]
Projected benefit obligations	$ 354.1	$ 303.8
Fair value of plan assets	300.4	255.5
Pension plans with an accumulated benefit obligation in excess of plan assets
Accumulated benefit obligations	37.0	30.0
Fair value of plan assets	$ 0.0	$ 0.0