Employee Benefit Plans (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 52	$ 55	$ 45
Interest cost		76	71	76
Expected return on plan assets		(107)	(112)	(103)
Amortization of prior service cost		15	19	23
Amortization of net actuarial loss		4	4	2
Net periodic benefit cost		40	37	43
Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		453	479	383
Interest cost		715	673	695
Expected return on plan assets		(828)	(873)	(807)
Amortization of prior service cost		8	15	20
Amortization of net actuarial loss		24	10	2
Net periodic benefit cost		372	304	293
Less: transfer to regulatory account	[1]	(34)	34	42
Total		$ 338	$ 338	$ 335

[1] The Utility recorded these amounts to a regulatory account as they are probable of recovery from customers in future rates.