Savings Plans, Pension Plans and Other Postretirement Employee Benefits (Pre-Tax Components Of Net Periodic Cost (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7,767	$ 8,454	$ 6,753
Interest cost	18,465	16,992	16,096
Expected return on plan assets	(22,190)	(20,035)	(18,406)
Amortization of prior service cost (credit)	211	186	288
Amortization of actuarial loss	13,497	16,589	14,484
Net periodic cost (benefit)	17,750	22,186	19,215
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	371	341	14
Interest cost	1,588	1,482	1,262
Amortization of prior service cost (credit)	(8,844)	(8,877)	(8,877)
Amortization of actuarial loss	1,012	1,311	1,537
Net periodic cost (benefit)	$ (5,873)	$ (5,743)	$ (6,064)