Benefit Plans (Schedule Of Components Of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Amortization:
Net periodic benefit cost (income)	$ (21)	$ (18)	$ (37)	$ (37)
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	20	19	61	57
Interest cost	69	72	207	216
Expected return on plan assets	(146)	(151)	(438)	(451)
Amortization:
Net loss	56	49	168	147
Prior service cost (credit)	1	1	3	3
Net periodic benefit cost (income)	0	(10)	1	(28)
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	3	13	12
Interest cost	15	17	52	57
Expected return on plan assets	(5)	0	(14)	0
Amortization:
Net loss	(1)	3	16	19
Prior service cost (credit)	(10)	(9)	(31)	(28)
Net periodic benefit cost (income)	$ 3	$ 14	$ 36	$ 60