Pension and Other Postretirement Employee Benefits (Components Of Net Periodic Cost (Benefit)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,021	$ 1,913
Interest cost	4,539	3,914
Expected return on plan assets	(5,554)	(4,708)
Amortization of prior service cost (credit)	53	46
Amortization of actuarial loss	3,427	4,150
Net periodic cost (benefit)	4,486	5,315
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	105	44
Interest cost	419	319
Amortization of prior service cost (credit)	(2,211)	(2,219)
Amortization of actuarial loss	307	355
Net periodic cost (benefit)	$ (1,380)	$ (1,501)