Pension And Other Postretirement Benefits Benefit Obligation (Schedule Of Net Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	$ 588.3
Balance, end of year	658.4	$ 588.3
Paid from Company assets for unfunded nonqualified benefits	1.7	1.6
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of period	708.8	756.3
Service cost	25.6	28.6	$ 26.4
Interest cost	30.0	27.3	27.8
Actuarial loss (gain)	117.0	(57.7)
Benefits paid from plan assets	(52.3)	(42.5)
Benefits paid from Company assets	(1.7)	(1.6)
Plan participants' contributions
Administrative expenses paid	(2.3)	(1.6)
Plan amendments
Benefit obligation, end of period	825.1	708.8	756.3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	588.3	585.4
Actual return on plan assets	114.7	(33.0)
Employer contributions	11.7	81.6
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant
Benefits paid	(54.0)	(44.1)
Administrative expenses paid	(2.3)	(1.6)
Balance, end of year	658.4	588.3	585.4
Unfunded status	166.7	120.5
Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of period	72.5	76.8
Service cost	2.0	2.3	2.3
Interest cost	2.9	2.6	2.9
Actuarial loss (gain)	3.0	(5.2)
Benefits paid from plan assets
Benefits paid from Company assets	(5.8)	(5.6)
Plan participants' contributions	1.4	1.6
Administrative expenses paid
Plan amendments	0.2
Benefit obligation, end of period	76.2	72.5	76.8
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year
Actual return on plan assets
Employer contributions	4.4	4.0
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	1.4	1.6
Benefits paid	(5.8)	(5.6)
Administrative expenses paid
Balance, end of year
Unfunded status	$ 76.2	$ 72.5