Pension and Postretirement Health and Life Benefits (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)
Gain (loss) related to litigation settlement	$ 43.5	$ 32.6
Defined Contribution Plan, Cost	2.0	1.6
Defined Benefit Plan, Actuarial (Gain) Loss From Remeasurement	50.5	(7.2)
Pension plan assets transferred for annuitization	30.4
Pension plan obligations transferred for annuitization	$ 30.4
Pension Plan, Defined Benefit [Member]
Approximate Number of Plan Participants	3,500
Defined Benefit Plan, Accumulated Benefit Obligation	$ 696.2	757.9
Gain (loss) related to litigation settlement	33.8
Defined Benefit Plan, Accumulated Benefit Obligation, Increase (Decrease) for Plan Amendment			$ 1.3
Defined Benefit Plan, Actuarial (Gain) Loss From Remeasurement	(28.7)	56.7
Pension Plan, Defined Benefit [Member] | Qualified Plan [Member]
Expected defined benefit plan contributions for next fiscal year for qualified plans	0.0
Pension Plan, Defined Benefit [Member] | Nonqualified Plan [Member]
Expected defined benefit plan contributions for next fiscal year for qualified plans	$ 0.4
Other Postretirement Benefits Plan [Member]
Approximate Number of Plan Participants	2,300
Gain (loss) related to litigation settlement	$ 9.7
Defined Benefit Plan, Accumulated Benefit Obligation, Increase (Decrease) for Plan Amendment				$ (10.0)	$ (3.6)	$ (6.8)
Expected defined benefit plan contributions for next fiscal year for qualified plans	7.0
Defined Benefit Plan, Actuarial (Gain) Loss From Remeasurement	$ (2.3)	$ (1.6)