Benefit Plans (Schedule Of Components Of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 17	$ 19
Interest cost	46	63
Expected return on plan assets	(131)	(126)
Amortization:
Net loss	33	27
Prior service cost (credit)	1	1
Net periodic benefit (income) cost	(34)	(16)
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	4
Interest cost	11	15
Expected return on plan assets	(4)	(3)
Amortization:
Net loss	7	3
Prior service cost (credit)	(6)	(7)
Net periodic benefit (income) cost	$ 13	$ 12