New And Significant Accounting Policies (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned		$ 118	$ 113
Interest cost		179	179
Expected return on plan assets		(193)	(207)
Amortization of prior service cost		(2)	2
Amortization of net actuarial loss		6	6
Net periodic benefit cost		108	93
Regulatory account transfer	[1]	(23)	(8)
Total		85	85
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned		15	13
Interest cost		19	19
Expected return on plan assets		(24)	(27)
Amortization of prior service cost		4	4
Amortization of net actuarial loss		1	1
Net periodic benefit cost		15	10
Regulatory account transfer	[1]	0	0
Total		$ 15	$ 10

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