Pension And Other Postretirement Benefits Benefit Obligation (Schedule Of Net Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	$ 658.4
Balance, end of year	722.0	$ 658.4
Paid from Company assets for unfunded nonqualified benefits	1.8	1.7
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of period	825.1	708.8
Service cost	29.2	25.6	$ 28.6
Interest cost	26.7	30.0	27.3
Actuarial loss (gain)	134.7	117.0
Benefits paid from plan assets	(2.1)	(52.3)
Benefits paid from Company assets	(1.8)	(1.7)
Plan participants' contributions
Administrative expenses paid	(3.2)	(2.3)
Plan amendments
Settlements	(86.8)
Benefit obligation, end of period	921.8	825.1	708.8
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	658.4	588.3
Actual return on plan assets	115.7	114.7
Employer contributions	41.8	11.7
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant
Benefits paid	(3.9)	(54.0)
Administrative expenses paid	(3.2)	(2.3)
Settlements	(86.8)
Balance, end of year	722.0	658.4	588.3
Unfunded status	199.8	166.7
Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of period	76.2	72.5
Service cost	2.1	2.0	2.3
Interest cost	2.4	2.9	2.6
Actuarial loss (gain)	4.9	3.0
Benefits paid from plan assets
Benefits paid from Company assets	(5.8)	(5.8)
Plan participants' contributions	1.1	1.4
Administrative expenses paid
Plan amendments		0.2
Settlements
Benefit obligation, end of period	80.9	76.2	72.5
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year
Actual return on plan assets
Employer contributions	4.7	4.4
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	1.1	1.4
Benefits paid	(5.8)	(5.8)
Administrative expenses paid
Settlements
Balance, end of year
Unfunded status	$ 80.9	$ 76.2