Fair Value Measurements and Credit Concentration (Assets and Liabilities Measured on Recurring Basis Table) (Details) (Recurring [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Assets
Cash and cash equivalents	$ 853		$ 901
Restricted cash and cash equivalents	186	[1]	135	[1]
Price risk management assets:
Energy commodities assets	1,676		2,068
Interest rate swaps assets	27		15
Foreign currency contracts assets	96
Cross-currency swaps assets	83		14
Total price risk management assets	1,882		2,097
NDT funds	764		712
Auction rate securities	19	[2]	19	[2]
Total assets	3,704		3,864
Price risk management liabilities:
Energy commodities liabilities	1,432		1,566
Interest rate swaps liabilities	69		80
Foreign currency contracts liabilities	3		44
Cross-currency swaps liabilities	1		4
Total price risk management liabilities	1,505		1,694
Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	8		11
United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	457		412
United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	68		60
United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	95		95
United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		9
Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	83		82
Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	40		40
Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		3
Receivables Payables Net [Member]
Price risk management assets:
NDT funds	1
Level 1 [Member]
Assets
Cash and cash equivalents	853		901
Restricted cash and cash equivalents	186	[1]	135	[1]
Price risk management assets:
Energy commodities assets	3		2
Interest rate swaps assets
Foreign currency contracts assets
Cross-currency swaps assets
Total price risk management assets	3		2
NDT funds	472		437
Auction rate securities
Total assets	1,514		1,475
Price risk management liabilities:
Energy commodities liabilities	2		2
Interest rate swaps liabilities
Foreign currency contracts liabilities
Cross-currency swaps liabilities
Total price risk management liabilities	2		2
Level 1 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	8		11
Level 1 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	342		308
Level 1 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	28		25
Level 1 [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	95		95
Level 1 [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds
Level 1 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds
Level 1 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds
Level 1 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds
Level 1 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	(1)		(2)
Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	1,651		2,037
Interest rate swaps assets	27		15
Foreign currency contracts assets	96
Cross-currency swaps assets	83		13
Total price risk management assets	1,857		2,065
NDT funds	292		275
Auction rate securities	3	[2]	3	[2]
Total assets	2,152		2,343
Price risk management liabilities:
Energy commodities liabilities	1,422		1,557
Interest rate swaps liabilities	69		80
Foreign currency contracts liabilities	3		44
Cross-currency swaps liabilities	1		4
Total price risk management liabilities	1,495		1,685
Level 2 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds
Level 2 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	115		104
Level 2 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	40		35
Level 2 [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds
Level 2 [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		9
Level 2 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	83		82
Level 2 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	40		40
Level 2 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		3
Level 2 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	2		2
Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	22		29
Interest rate swaps assets
Foreign currency contracts assets
Cross-currency swaps assets			1
Total price risk management assets	22		30
NDT funds
Auction rate securities	16	[2]	16	[2]
Total assets	38		46
Price risk management liabilities:
Energy commodities liabilities	8		7
Interest rate swaps liabilities
Foreign currency contracts liabilities
Cross-currency swaps liabilities
Total price risk management liabilities	8		7
Level 3 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member]
Assets
Cash and cash equivalents	147		413
Restricted cash and cash equivalents	122	[1]	63	[1]
Price risk management assets:
Energy commodities assets	1,676		2,068
Total price risk management assets	1,676		2,068
NDT funds	764		712
Auction rate securities	16	[2]	16	[2]
Total assets	2,725		3,272
Price risk management liabilities:
Energy commodities liabilities	1,432		1,566
Total price risk management liabilities	1,432		1,566
PPL Energy Supply LLC [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	8		11
PPL Energy Supply LLC [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	457		412
PPL Energy Supply LLC [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	68		60
PPL Energy Supply LLC [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	95		95
PPL Energy Supply LLC [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		9
PPL Energy Supply LLC [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	83		82
PPL Energy Supply LLC [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	40		40
PPL Energy Supply LLC [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		3
PPL Energy Supply LLC [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	1
PPL Energy Supply LLC [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	147		413
Restricted cash and cash equivalents	122	[1]	63	[1]
Price risk management assets:
Energy commodities assets	3		2
Total price risk management assets	3		2
NDT funds	472		437
Auction rate securities
Total assets	744		915
Price risk management liabilities:
Energy commodities liabilities	2		2
Total price risk management liabilities	2		2
PPL Energy Supply LLC [Member] | Level 1 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	8		11
PPL Energy Supply LLC [Member] | Level 1 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	342		308
PPL Energy Supply LLC [Member] | Level 1 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	28		25
PPL Energy Supply LLC [Member] | Level 1 [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	95		95
PPL Energy Supply LLC [Member] | Level 1 [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 1 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 1 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 1 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 1 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	(1)		(2)
PPL Energy Supply LLC [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	1,651		2,037
Total price risk management assets	1,651		2,037
NDT funds	292		275
Auction rate securities	3	[2]	3	[2]
Total assets	1,946		2,315
Price risk management liabilities:
Energy commodities liabilities	1,422		1,557
Total price risk management liabilities	1,422		1,557
PPL Energy Supply LLC [Member] | Level 2 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 2 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	115		104
PPL Energy Supply LLC [Member] | Level 2 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	40		35
PPL Energy Supply LLC [Member] | Level 2 [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 2 [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		9
PPL Energy Supply LLC [Member] | Level 2 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	83		82
PPL Energy Supply LLC [Member] | Level 2 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	40		40
PPL Energy Supply LLC [Member] | Level 2 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		3
PPL Energy Supply LLC [Member] | Level 2 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	2		2
PPL Energy Supply LLC [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	22		29
Total price risk management assets	22		29
NDT funds
Auction rate securities	13	[2]	13	[2]
Total assets	35		42
Price risk management liabilities:
Energy commodities liabilities	8		7
Total price risk management liabilities	8		7
PPL Energy Supply LLC [Member] | Level 3 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds
PPL Electric Utilities Corp [Member]
Assets
Cash and cash equivalents	31		140
Restricted cash and cash equivalents	12	[3]	13	[3]
Price risk management assets:
Total assets	43		153
PPL Electric Utilities Corp [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	31		140
Restricted cash and cash equivalents	12	[3]	13	[3]
Price risk management assets:
Total assets	43		153
PPL Electric Utilities Corp [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Total assets
PPL Electric Utilities Corp [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Total assets
LG And E And KU Energy LLC [Member]
Assets
Cash and cash equivalents	52		43
Restricted cash and cash equivalents	27	[4]	32	[4]
Price risk management assets:
Interest rate swaps assets	24		14
Total price risk management assets	24		14
Total assets	103		89
Price risk management liabilities:
Interest rate swaps liabilities	54		58
Total price risk management liabilities	54		58
LG And E And KU Energy LLC [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	52		43
Restricted cash and cash equivalents	27	[4]	32	[4]
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets	79		75
Price risk management liabilities:
Interest rate swaps liabilities
Total price risk management liabilities
LG And E And KU Energy LLC [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Interest rate swaps assets	24		14
Total price risk management assets	24		14
Total assets	24		14
Price risk management liabilities:
Interest rate swaps liabilities	54		58
Total price risk management liabilities	54		58
LG And E And KU Energy LLC [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets
Price risk management liabilities:
Interest rate swaps liabilities
Total price risk management liabilities
Louisville Gas And Electric Co [Member]
Assets
Cash and cash equivalents	34		22
Restricted cash and cash equivalents	27	[4]	32	[4]
Price risk management assets:
Interest rate swaps assets	12		7
Total price risk management assets	12		7
Total assets	73		61
Price risk management liabilities:
Interest rate swaps liabilities	54		58
Total price risk management liabilities	54		58
Louisville Gas And Electric Co [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	34		22
Restricted cash and cash equivalents	27	[4]	32	[4]
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets	61		54
Price risk management liabilities:
Interest rate swaps liabilities
Total price risk management liabilities
Louisville Gas And Electric Co [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Interest rate swaps assets	12		7
Total price risk management assets	12		7
Total assets	12		7
Price risk management liabilities:
Interest rate swaps liabilities	54		58
Total price risk management liabilities	54		58
Louisville Gas And Electric Co [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets
Price risk management liabilities:
Interest rate swaps liabilities
Total price risk management liabilities
Kentucky Utilities Co [Member]
Assets
Cash and cash equivalents	16		21
Price risk management assets:
Interest rate swaps assets	12		7
Total price risk management assets	12		7
Total assets	28		28
Kentucky Utilities Co [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	16		21
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets	16		21
Kentucky Utilities Co [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Price risk management assets:
Interest rate swaps assets	12		7
Total price risk management assets	12		7
Total assets	12		7
Kentucky Utilities Co [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets

[1] Current portion is included in "Restricted cash and cash equivalents" and the long-term portion is included in "Other noncurrent assets" on the Balance Sheets.

[2] Included in "Other investments" on the Balance Sheets.

[3] Current portion is included in "Other current assets" and the long-term portion is included in "Other noncurrent assets" on the Balance Sheets.

[4] Included in "Other noncurrent assets" on the Balance Sheets.