Other Income (Expense) - net (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Other income [Line Items]
Other income	$ 74	$ 10	$ 88	$ 19
Other Expense [Line Items]
Other expense	108	10	127	11
Other Income (Expense) - net	(34)	0	(39)	8
Earnings On Securities In NDT Funds [Member]
Other income [Line Items]
Other income	3	5	18	11
Interest Income [Member]
Other income [Line Items]
Other income	2	0	4	1
AFUDC [Member]
Other income [Line Items]
Other income	2	1	3	2
Net Hedge Gains On 2011 Bridge Facility [Member]
Other income [Line Items]
Other income	62	0	55	0
Miscellaneous Domestic Other Income [Member]
Other income [Line Items]
Other income	4	3	7	4
Miscellaneous International Other Income [Member]
Other income [Line Items]
Other income	1	1	1	1
Economic Foreign Currency Exchange Contracts [Member]
Other Expense [Line Items]
Other expense	(2)	0	0	(2)
Charitable Contributions [Member]
Other Expense [Line Items]
Other expense	2	1	5	2
LKE Other Acquisition-related Costs [Member]
Other Expense [Line Items]
Other expense	0	7	0	7
WPD Midlands Other Acquisition-related Costs [Member]
Other Expense [Line Items]
Other expense	26	0	36	0
Foreign Currency Loss On 2011 Bridge Facility [Member]
Other Expense [Line Items]
Other expense	58	0	58	0
UK Stamp Duty Tax [Member]
Other Expense [Line Items]
Other expense	21	0	21	0
Miscellaneous Domestic Other Expense [Member]
Other Expense [Line Items]
Other expense	1	1	4	3
Miscellaneous International Other Expense [Member]
Other Expense [Line Items]
Other expense	$ 2	$ 1	$ 3	$ 1