Pension And OPEB (Components Of Net Periodic Benefit Cost) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 26	$ 29	$ 52	$ 58
Interest Cost	59	53	118	107
Expected Return on Plan Assets	(100)	(87)	(200)	(174)
Amortization of Prior Service Cost	(4)	(4)	(9)	(9)
Amortization of Actuarial Loss	14	47	28	94
Total Benefit Costs	(5)	38	(11)	76
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	4	5	9	10
Interest Cost	17	16	34	32
Expected Return on Plan Assets	(6)	(5)	(13)	(10)
Amortization of Prior Service Cost	(3)	(3)	(7)	(7)
Amortization of Actuarial Loss	6	10	12	21
Total Benefit Costs	$ 18	$ 23	$ 35	$ 46