Pension and Other Postretirement Employee Benefits (Components Of Net Periodic Cost (Benefit)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,233	$ 1,942	$ 6,699	$ 5,825
Interest cost	3,066	4,618	9,198	13,849
Expected return on plan assets	(3,869)	(5,548)	(11,606)	(16,643)
Amortization of prior service cost (credit)	29	52	85	158
Amortization of actuarial loss	3,856	3,374	11,569	10,122
Net periodic cost (benefit) before pension settlement charge			15,945	13,311
Pension settlement charge			42,988
Total net periodic cost (benefit)	5,315	4,438	58,933	13,311
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	127	93	381	278
Interest cost	376	397	1,127	1,191
Amortization of prior service cost (credit)	(319)	(2,211)	(957)	(6,633)
Amortization of actuarial loss	418	253	1,254	760
Net periodic cost (benefit) before pension settlement charge			1,805	(4,404)
Total net periodic cost (benefit)	$ 602	$ (1,468)	$ 1,805	$ (4,404)