Pension and Other Postretirement Employee Benefits (Components Of Net Periodic Cost (Benefit)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,862	$ 2,178	$ 3,883	$ 4,091
Interest cost	4,692	4,390	9,231	8,304
Expected return on plan assets	(5,541)	(5,135)	(11,095)	(9,843)
Amortization of prior service cost (credit)	53	47	106	93
Amortization of actuarial loss	3,321	4,144	6,748	8,294
Net periodic cost (benefit)	4,387	5,624	8,873	10,939
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	80	99	185	143
Interest cost	375	381	794	700
Amortization of prior service cost (credit)	(2,211)	(2,220)	(4,422)	(4,439)
Amortization of actuarial loss	200	301	507	656
Net periodic cost (benefit)	$ (1,556)	$ (1,439)	$ (2,936)	$ (2,940)