Benefit Plans (Schedule Of Components Of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Termination and curtailment				$ 20
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 19	$ 18	$ 57	55
Interest cost	72	70	216	211
Expected return on plan assets	(151)	(139)	(451)	(416)
Amortization of net loss	49	43	147	130
Amortization of prior service cost (credit)	1	2	3	4
Termination and curtailment	0	0	0	20
Net periodic benefit (income) cost	(10)	(6)	(28)	4
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	4	12	12
Interest cost	17	18	57	58
Expected return on plan assets	0	0	0	0
Amortization of net loss	3	3	19	19
Amortization of prior service cost (credit)	(9)	(10)	(28)	(29)
Termination and curtailment	0	0	0	0
Net periodic benefit (income) cost	$ 14	$ 15	$ 60	$ 60