Benefit Plans (Schedule Of Components Of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Amortization:
Net periodic benefit cost (income)	$ (9)	$ (11)	$ (16)	$ (19)
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	20	19	41	38
Interest cost	70	72	138	144
Expected return on plan assets	(146)	(150)	(292)	(300)
Amortization:
Net loss	55	48	112	98
Prior service cost (credit)	1	1	2	2
Net periodic benefit cost (income)	0	(10)	1	(18)
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	5	9	9
Interest cost	18	20	37	40
Expected return on plan assets	(4)	0	(9)	0
Amortization:
Net loss	8	8	17	16
Prior service cost (credit)	(11)	(10)	(21)	(19)
Net periodic benefit cost (income)	$ 16	$ 23	$ 33	$ 46