Pension And OPEB (Components Of Net Periodic Benefit Cost) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 26	$ 29	$ 78	$ 87
Interest Cost	58	54	176	161
Expected Return on Plan Assets	(99)	(87)	(299)	(261)
Amortization of Prior Service Cost	(5)	(5)	(14)	(14)
Amortization of Actuarial Loss	14	47	42	141
Total Benefit Costs	(6)	38	(17)	114
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	5	6	14	16
Interest Cost	18	15	52	47
Expected Return on Plan Assets	(7)	(6)	(20)	(16)
Amortization of Prior Service Cost	(4)	(4)	(11)	(11)
Amortization of Actuarial Loss	6	11	18	32
Total Benefit Costs	$ 18	$ 22	$ 53	$ 68