Retirement Benefits (Components Of Net Periodic Benefit Cost) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Pension Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 22		$ 20		$ 46		$ 41
Interest cost	41		41		81		83
Expected return on plan assets	(54)		(52)		(108)		(104)
Prior service cost (benefit)	(1)		(1)		(2)		(2)
Actuarial loss	24		18		46		37
Net periodic benefit cost	32	[1]	26	[1]	63	[1]	55	[1]
Postretirement Benefit Costs [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	5		5		11		11
Interest cost	11		11		23		24
Expected return on plan assets	(15)		(14)		(31)		(28)
Prior service cost (benefit)	(1)		(1)		(2)		(2)
Actuarial loss	2		(1)		4		2
Net periodic benefit cost	$ 2	[1]		[1]	$ 5	[1]	$ 7	[1]

[1] Excludes the EEI plans as they are included in discontinued operations.