Pension And Other Postretirement Benefits (Schedule Of Changes In Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	$ 588.3	$ 588.3
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
Investments Measured at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	370.2	370.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	370.2
Balance, end of year	416.5	370.2
Quoted Prices in Active Markets for Identical Inputs (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	207.7	207.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	207.7
Balance, end of year	219.5	207.7
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	10.4	7.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	10.4	7.7
Realized gains/(losses)	0.1	0.1
Unrealized gains/(losses)	1.5
Purchases	11.2	4.1
Sales	(0.8)	(1.5)
Balance, end of year	22.4	10.4
Equity Securities - U.S.
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	30.0	30.0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	30.0
Balance, end of year	40.0	30.0
Equity Securities - U.S. | Investments Measured at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	10.7	10.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	10.7
Balance, end of year	14.0	10.7
Equity Securities - U.S. | Quoted Prices in Active Markets for Identical Inputs (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	19.3	19.3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	19.3
Balance, end of year	26.0	19.3
Equity Securities - International
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	47.6	47.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	47.6
Balance, end of year	58.6	47.6
Equity Securities - International | Investments Measured at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	20.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, end of year	20.7
Equity Securities - International | Quoted Prices in Active Markets for Identical Inputs (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	47.6	47.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	47.6
Balance, end of year	37.9	47.6
Fixed Income Investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	416.6	416.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	416.6
Balance, end of year	447.9	416.6
Fixed Income Investments | Investments Measured at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	291.7	291.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	291.7
Balance, end of year	312.7	291.7
Fixed Income Investments | Quoted Prices in Active Markets for Identical Inputs (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	124.9	124.9
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	124.9
Balance, end of year	135.2	124.9
Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	30.7	30.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	30.7
Balance, end of year	32.0	30.7
Hedge Funds | Investments Measured at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	30.7	30.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	30.7
Balance, end of year	32.0	30.7
Private Markets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	22.3	22.3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	22.3
Balance, end of year	28.0	22.3
Private Markets | Investments Measured at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	16.3	16.3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	16.3
Balance, end of year	17.0	16.3
Private Markets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	11.0	3.8
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	6.0	3.8
Realized gains/(losses)	0.1	0.1
Unrealized gains/(losses)	0.7
Purchases	4.4	3.2
Sales	(0.2)	(1.1)
Balance, end of year	11.0	6.0
Other Investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	38.5	38.5
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	38.5
Balance, end of year	49.5	38.5
Other Investments | Investments Measured at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	18.2	18.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	18.2
Balance, end of year	17.7	18.2
Other Investments | Quoted Prices in Active Markets for Identical Inputs (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	15.9	15.9
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	15.9
Balance, end of year	20.4	15.9
Other Investments | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	4.4	4.4
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	4.4	3.9
Realized gains/(losses)
Unrealized gains/(losses)	0.8
Purchases	6.8	0.9
Sales	(0.6)	(0.4)
Balance, end of year	11.4	4.4
Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	2.6	2.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	2.6
Balance, end of year	2.4	2.6
Short-term Investments | Investments Measured at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets measured at net asset value	2.6	2.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance, beginning of year	2.6
Balance, end of year	$ 2.4	$ 2.6