Benefit Plans (Schedule Of Components Of Net Periodic Pension and Postretirement Costs) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 18	$ 21
Interest cost	71	84
Expected return on plan assets	(138)	(135)
Amortization of net loss	44	59
Amortization of prior service cost (credit)	1	2
Termination and curtailment	20	0
Net periodic benefit cost	16	31
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4
Interest cost	21	26
Expected return on plan assets	0	0
Amortization of net loss	7	12
Amortization of prior service cost (credit)	(10)	(10)
Termination and curtailment	0	0
Net periodic benefit cost	$ 22	$ 32