Pension and Other Postretirement Employee Benefits (Components Of Net Periodic Cost (Benefit)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,290	$ 2,021
Interest cost	3,564	4,539
Expected return on plan assets	(4,586)	(5,554)
Amortization of prior service cost (credit)	28	53
Amortization of actuarial loss	4,154	3,427
Net periodic cost (benefit) before pension settlement charge	5,450	4,486
Pension settlement charge	42,988
Total net periodic cost (benefit)	48,438	4,486
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	143	105
Interest cost	375	419
Amortization of prior service cost (credit)	(319)	(2,211)
Amortization of actuarial loss	419	307
Net periodic cost (benefit) before pension settlement charge	618	(1,380)
Total net periodic cost (benefit)	$ 618	$ (1,380)