New And Significant Accounting Policies (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2017	Sep. 30, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 118		$ 113		$ 354	$ 339
Interest cost	178		179		535	537
Expected return on plan assets	(193)		(207)		(578)	(621)
Amortization of prior service cost	(1)		2		(5)	6
Amortization of net actuarial loss	6		6		17	18
Net periodic benefit cost	108		93		323	279
Regulatory account transfer	(23)	[1]	(8)	[1]	(69)	(25)
Total	85		85		254	254
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	14		13		44	39
Interest cost	20		19		58	57
Expected return on plan assets	(24)		(26)		(73)	(80)
Amortization of prior service cost	4		3		12	11
Amortization of net actuarial loss	1		1		3	3
Net periodic benefit cost	15		10		44	30
Regulatory account transfer	0	[1]	0	[1]	0	0
Total	$ 15		$ 10		$ 44	$ 30

[1] The Utility recorded these amounts to a regulatory account since they are probable of recovery from, or refund to, customers in futures rates.