New And Significant Accounting Policies (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2017	Jun. 30, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 118		$ 113		$ 236	$ 226
Interest cost	178		179		357	358
Expected return on plan assets	(192)		(207)		(385)	(414)
Amortization of prior service cost	(2)		2		(4)	4
Amortization of net actuarial loss	5		6		11	12
Net periodic benefit cost	107		93		215	186
Regulatory account transfer	(23)	[1]	(8)	[1]	(46)	(17)
Total	84		85		169	169
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	15		13		30	26
Interest cost	19		19		38	38
Expected return on plan assets	(25)		(27)		(49)	(54)
Amortization of prior service cost	4		4		8	8
Amortization of net actuarial loss	1		1		2	2
Net periodic benefit cost	14		10		29	20
Regulatory account transfer	0	[1]	0	[1]	0	0
Total	$ 14		$ 10		$ 29	$ 20

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