Pension and Other Post-Retirement Benefits - Expected Benefit Plan Payments (Details) $ in Millions	Dec. 31, 2019 USD ($)
Qualified Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
2018	$ 28.8
2019	28.6
2020	28.4
2021	28.6
2022	29.9
Years 2025-2029	141.3
Total	285.6
Nonqualified Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
2018	3.2
2019	3.1
2020	3.3
2021	3.5
2022	3.5
Years 2025-2029	16.7
Total	33.3
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2018	3.0
2019	2.4
2020	2.2
2021	2.0
2022	1.9
Years 2025-2029	7.8
Total	$ 19.3