Acquisitions, Development and Divestures (Details) (USD $)	3 Months Ended			12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014		Dec. 31, 2014	Apr. 29, 2015
Divestitures - Anticipated Spinoff of PPL Energy Supply (Numeric) [Abstract]
Spinoff transaction costs	$ 2,000,000	$ 0
Discontinued Operations (Details) [Abstract]
Income (Loss) from Discontinued Operations (net of income taxes)	0	(8,000,000)
Solar Generation Facility [Member]
Development Projects [Abstract]
Planned capacity expansion (in MW)	10
Expected capital cost of an expansion project	36,000,000
LGE [Member]
Development Projects [Abstract]
Generating units anticipated to be retired at the Cane Run plant in the third quarter of 2015	2
PPL Energy Supply Spinoff [Member]
Divestitures - Anticipated Spinoff of PPL Energy Supply (Numeric) [Abstract]
Spinoff agreement execution date	Jun. 09, 2014
Certain details of spinoff transaction	PPL and PPL Energy Supply executed definitive agreements with affiliates of Riverstone to combine their competitive power generation businesses into a new, stand-alone, publicly traded company named Talen Energy. Under the terms of the agreements, at closing, PPL will spin off to PPL shareowners a newly formed entity, Talen Energy Holdings, Inc. (Holdco), which at such time will own all of the membership interests of PPL Energy Supply and all of the common stock of Talen Energy. Immediately following the spinoff, Holdco will merge with a special purpose subsidiary of Talen Energy, with Holdco continuing as the surviving company to the merger and as a wholly owned subsidiary of Talen Energy and the sole owner of PPL Energy Supply. Substantially contemporaneous with the spinoff and merger, RJS Power will be contributed by its owners to become a subsidiary of Talen Energy.
Initial percent ownership in new company, Talen Energy, by PPL shareowners	65.00%
Initial percent ownership in new company, Talen Energy, by Riverstone Holdings, LLC	35.00%
Minimum capacity of revolving credit facility for Talen required at closing under agreement terms	1,000,000,000
Capacity, in total, to be divested in connection with the spinoff (in MW)	1,300
Number of asset groups proposed to be divested, one of which to be selected	2
Number of asset groups that will be divested	1
Maximum term after closing to divest an asset group (in months)	within 12 months
Spinoff expected completion date	June 1, 2015.
Number of shares of Talen common stock for one share of PPL common stock					0.125
Unamortized losses on interest rate swaps deferred in accumulated other comprehensive income	(55,000,000)
Montana Hydroelectric Generating Facilities [Member]
Divestitures - Montana Hydro Sale Agreement (Numeric) [Abstract]
Capacity of facilities sold (in MW)	633
Agreed upon sales price for disposal of hydroelectric facilities owned by PPL Montana	900,000,000
Number of hydroelectric facilities owned by PPL Montana sold	11
Discontinued Operations (Details) [Abstract]
Operating revenues		29,000,000
Interest expense		2,000,000	[1]
Discontinued operations		(10,000,000)	[2]
Income (Loss) from Discontinued Operations (net of income taxes)		(8,000,000)	[2]
Spinoff [Member] | PPL Energy Supply Spinoff [Member]
Divestitures - Anticipated Spinoff of PPL Energy Supply (Numeric) [Abstract]
Amount of accrued libality for seperation benefits	19,000,000			30,000,000
Spinoff transaction costs	6,000,000			27,000,000
Spinoff [Member] | PPL Energy Supply Spinoff [Member] | Minimum [Member]
Divestitures - Anticipated Spinoff of PPL Energy Supply (Numeric) [Abstract]
Additional seperation costs to be recognized at the spinoff closing date	30,000,000
Spinoff transaction costs	60,000,000
Spinoff [Member] | PPL Energy Supply Spinoff [Member] | Maximum [Member]
Divestitures - Anticipated Spinoff of PPL Energy Supply (Numeric) [Abstract]
Additional seperation costs to be recognized at the spinoff closing date	40,000,000
Spinoff transaction costs	70,000,000
Spinoff [Member] | PPL Energy Supply Spinoff [Member] | Other Operation And Maintenance [Member]
Divestitures - Anticipated Spinoff of PPL Energy Supply (Numeric) [Abstract]
Spinoff transaction costs	4,000,000
Spinoff [Member] | PPL Energy Supply Spinoff [Member] | Other Income (Expense) Net [Member]
Divestitures - Anticipated Spinoff of PPL Energy Supply (Numeric) [Abstract]
Spinoff transaction costs	2,000,000
LG And E And KU Energy LLC [Member] | Solar Generation Facility [Member]
Development Projects [Abstract]
Planned capacity expansion (in MW)	10
Expected capital cost of an expansion project	36,000,000
LG And E And KU Energy LLC [Member] | LGE [Member]
Development Projects [Abstract]
Generating units anticipated to be retired at the Cane Run plant in the third quarter of 2015	2
Louisville Gas And Electric Co [Member]
Development Projects [Abstract]
Generating units anticipated to be retired at the Cane Run plant in the third quarter of 2015	2
Louisville Gas And Electric Co [Member] | Solar Generation Facility [Member]
Development Projects [Abstract]
Planned capacity expansion (in MW)	10
Expected capital cost of an expansion project	36,000,000
Kentucky Utilities Co [Member] | Solar Generation Facility [Member]
Development Projects [Abstract]
Planned capacity expansion (in MW)	10
Expected capital cost of an expansion project	$ 36,000,000

[1] Represents allocated interest expense based upon the discontinued operations share of the net assets of PPL Energy Supply.

[2] Includes an impairment charge related to the Kerr Dam Project. See Note 13 for additional information.