Benefit Plans (Schedule Of Components Of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 17	$ 21
Interest cost	77	68
Expected return on plan assets	(145)	(146)
Amortization:
Net loss	42	57
Prior service cost (credit)	1	1
Curtailment	7	0
Net periodic benefit (income) cost	(1)	1
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4
Interest cost	20	19
Expected return on plan assets	(4)	(5)
Amortization:
Net loss	3	9
Prior service cost (credit)	(7)	(10)
Curtailment	5	0
Net periodic benefit (income) cost	$ 21	$ 17