Fair Value Measurements and Credit Concentration (Nonrecurring Fair Value Measurements and Credit Concentration) (Details) (USD $)	Jun. 30, 2012		Dec. 31, 2011
Credit Concentration Associated with Financial Instruments (Numeric) [Abstract]
Gross credit exposure from energy trading partners	$ 2,900,000,000
Net credit exposure to energy trading partners	843,000,000
Dollar exposure to top ten energy trading counterparties	429,000,000
Percentage exposure to top ten energy trading counterparties	51.00%
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Contract adjustment payments	152,000,000	[1]	198,000,000	[1]
Long-term debt	18,710,000,000		17,993,000,000
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Contract adjustment payments	154,000,000		198,000,000
Long-term debt	20,402,000,000		19,392,000,000
PPL Energy Supply LLC [Member]
Credit Concentration Associated with Financial Instruments (Numeric) [Abstract]
Gross credit exposure from energy trading partners	2,900,000,000
Net credit exposure to energy trading partners	842,000,000
Dollar exposure to top ten energy trading counterparties	429,000,000
Percentage exposure to top ten energy trading counterparties	51.00%
PPL Energy Supply LLC [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	3,279,000,000		3,024,000,000
PPL Energy Supply LLC [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	3,663,000,000		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	1,718,000,000		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	2,020,000,000		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	4,333,000,000		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	1,166,000,000		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	$ 2,004,000,000		$ 2,000,000,000

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