Segment and Related Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015		Dec. 31, 2015
Income Statement Data
Revenues		$ 2,011	$ 2,230
Net Income		481	647
Balance Sheet Data
Assets		38,709			$ 39,301
United Kingdom Regulated [Member]
Income Statement Data
Revenues		595	697
Net Income	[1]	289	375
Balance Sheet Data
Assets	[2]	15,802			16,669
Segment (Numeric) [Abstract]
Net property, plant and equipment not subject to accounting for the effects of certain types of regulation		11,400			12,200
Kentucky Regulated [Member]
Income Statement Data
Revenues		826	899
Net Income		112	109
Balance Sheet Data
Assets		13,777			13,756
Pennsylvania Regulated [Member]
Income Statement Data
Revenues		585	630
Net Income		94	87
Balance Sheet Data
Assets		8,720			8,511
Corporate And Other [Member]
Income Statement Data
Revenues		5	4
Net Income		(14)	(19)
Balance Sheet Data
Assets	[3]	410			$ 365
Discontinued Operations [Member]
Income Statement Data
Net Income		$ 0	$ 95	[4]

[1] Includes unrealized gains and losses from hedging foreign-currency related economic activity . See Note 14 for additional information.

[2] Includes $11.4 billion and $12.2 billion of net PP&E as of March 31, 2016 and December 31, 2015. WPD is not subject to accounting for the effects of certain types of regulation as prescribed by GAAP.

[3] Primarily consists of unallocated items, including c ash, PP&E and the elimination of inter-segment transactions.

[4] See Note 8 for additional information.