Benefit Plans (Schedule Of Components Of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Termination and curtailment		$ 20
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 19	18
Interest cost	72	71
Expected return on plan assets	(150)	(138)
Amortization of net loss	50	44
Amortization of prior service cost (credit)	1	1
Termination and curtailment	0	20
Net periodic benefit (income) cost	(8)	16
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4
Interest cost	20	21
Expected return on plan assets	0	0
Amortization of net loss	8	7
Amortization of prior service cost (credit)	(9)	(10)
Termination and curtailment	0	0
Net periodic benefit (income) cost	$ 23	$ 22