Fair Value Measurements and Credit Concentration (Nonrecurring Fair Value Measurements and Credit Concentration) (Details) (USD $)	Sep. 30, 2012		Dec. 31, 2011
Credit Concentration Associated with Financial Instruments (Numeric) [Abstract]
Gross credit exposure from energy trading partners	$ 2,100,000,000
Net credit exposure to energy trading partners	657,000,000
Dollar exposure to top ten energy trading counterparties	345,000,000
Percentage exposure to top ten energy trading counterparties	52.00%
Number of counterparties in top ten that have investment grade credit rating	10
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Contract adjustment payments	128,000,000	[1]	198,000,000	[1]
Long-term debt	19,024,000,000	[2]	17,993,000,000	[2]
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Contract adjustment payments	116,000,000		198,000,000
Long-term debt	21,091,000,000		19,392,000,000
PPL Energy Supply LLC [Member]
Credit Concentration Associated with Financial Instruments (Numeric) [Abstract]
Gross credit exposure from energy trading partners	2,100,000,000
Net credit exposure to energy trading partners	656,000,000
Dollar exposure to top ten energy trading counterparties	345,000,000
Percentage exposure to top ten energy trading counterparties	53.00%
Number of counterparties in top ten that have investment grade credit rating	10
PPL Energy Supply LLC [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	3,275,000,000	[2]	3,024,000,000	[2]
PPL Energy Supply LLC [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	3,691,000,000		3,397,000,000
PPL Electric Utilities Corp [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	1,967,000,000		1,718,000,000
PPL Electric Utilities Corp [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	2,252,000,000		2,012,000,000
LG And E And KU Energy LLC [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	4,074,000,000		4,073,000,000
LG And E And KU Energy LLC [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	4,385,000,000		4,306,000,000
Louisville Gas And Electric Co [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	1,112,000,000		1,112,000,000
Louisville Gas And Electric Co [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	1,172,000,000		1,164,000,000
Kentucky Utilities Co [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	1,842,000,000		1,842,000,000
Kentucky Utilities Co [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	$ 2,021,000,000		$ 2,000,000,000

[1] Reflected in "Other current liabilities" and "Other deferred credits and noncurrent liabilities" on the Balance Sheets.

[2] Includes "Long-term Debt" and "Long-term debt due within one year" on the Balance Sheets.