Segment and Related Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Income Statement Data
Revenues	$ 3,165		$ 1,194	[1]
Net Income	647		316
Balance Sheet Data
Assets	48,921				48,864
United Kingdom Regulated [Member]
Income Statement Data
Revenues	697		648
Net Income	375		206	[1]
Balance Sheet Data
Assets	16,275				16,005
Kentucky Regulated [Member]
Income Statement Data
Revenues	899		934
Net Income	109		107
Balance Sheet Data
Assets	13,109				13,062
Pennsylvania Regulated [Member]
Income Statement Data
Revenues	630		591
Net Income	87		85
Balance Sheet Data
Assets	7,921				7,785
Supply [Member]
Income Statement Data
Revenues	937		(982)	[1]
Net Income	95	[1]	(75)	[1]
Balance Sheet Data
Assets	10,631				11,025
Corporate And Other [Member]
Income Statement Data
Revenues	2		3
Net Income	(19)	[2]	(7)
Balance Sheet Data
Assets	985	[3]			987	[3]
Intersegment Eliminations [Member] | Supply [Member]
Income Statement Data
Revenues	$ (9)		$ (27)

[1] Includes unrealized gains and losses from economic activity. See Note 14 for additional information.

[2] 2015 includes most of the transaction and transition costs related to the anticipated spinoff of PPL Energy Supply. See Note 8 for additional information.

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