Benefit Plans (Schedule Of Components Of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Termination and curtailment				$ 20
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 19	$ 19	$ 38	37
Interest cost	72	70	144	141
Expected return on plan assets	(150)	(139)	(300)	(277)
Amortization of net loss	48	43	98	87
Amortization of prior service cost (credit)	1	1	2	2
Termination and curtailment	0	0	0	20
Net periodic benefit (income) cost	(10)	(6)	(18)	10
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	4	9	8
Interest cost	20	19	40	40
Expected return on plan assets	0	0	0	0
Amortization of net loss	8	9	16	16
Amortization of prior service cost (credit)	(10)	(9)	(19)	(19)
Termination and curtailment	0	0	0	0
Net periodic benefit (income) cost	$ 23	$ 23	$ 46	$ 45