Benefit Plans, Fair Values by Asset Category (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Weighted average asset allocations value [Abstract]
Fair value of plan assets	$ 340.0	$ 296.7
Equity Securities [Member]
Weighted average asset allocations value [Abstract]
Fair value of plan assets	187.5	162.8
Fixed Income Securities [Member]
Weighted average asset allocations value [Abstract]
Fair value of plan assets	98.8	113.6
Real Estate [Member]
Weighted average asset allocations value [Abstract]
Fair value of plan assets	0.9	2.3
Other [Member]
Weighted average asset allocations value [Abstract]
Fair value of plan assets	$ 52.8	$ 18.0