Pension and Postretirement Plans - Narratives (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Expected future employer contributions, next fiscal year	$ 8.0
Contributions to pension plans	1.5	$ 1.9
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Contributions to pension plans	1.4	$ 1.1
Qualified Plan [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Expected future employer contributions, next fiscal year	6.0
Nonqualified Plan [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Expected future employer contributions, next fiscal year	$ 3.0