Fair Value Measurements and Credit Concentration (Assets and Liabilities Measured on Recurring Basis Table) (Details) (Recurring [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Assets
Cash and cash equivalents	$ 901		$ 1,202
Restricted cash and cash equivalents	135	[1]	209	[1]
Price risk management assets:
Energy commodities assets	2,068		3,423
Interest rate swaps assets	15		3
Foreign currency contracts assets			18
Cross-currency swaps assets	14		24
Total price risk management assets	2,097		3,468
NDT funds	712		640
Auction rate securities	19	[2]	24	[2]
Total assets	3,864		5,543
Price risk management liabilities:
Energy commodities liabilities	1,566		2,345
Interest rate swaps liabilities	80		63
Foreign currency contracts liabilities	44
Cross-currency swaps liabilities	4		2
Total price risk management liabilities	1,694		2,410
Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	11		12
US Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	412		357
US Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	60		52
US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	95		86
US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		10
Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	82		83
Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	40		38
Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		2
Receivables Payables Net [Member]
Price risk management assets:
NDT funds
Level 1 [Member]
Assets
Cash and cash equivalents	901		1,202
Restricted cash and cash equivalents	135	[1]	209	[1]
Price risk management assets:
Energy commodities assets	2		3
Interest rate swaps assets
Foreign currency contracts assets
Cross-currency swaps assets
Total price risk management assets	2		3
NDT funds	437		384
Auction rate securities
Total assets	1,475		1,798
Price risk management liabilities:
Energy commodities liabilities	2		1
Interest rate swaps liabilities
Foreign currency contracts liabilities
Cross-currency swaps liabilities
Total price risk management liabilities	2		1
Level 1 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	11		12
Level 1 [Member] | US Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	308		267
Level 1 [Member] | US Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	25		22
Level 1 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	95		86
Level 1 [Member] | US 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	(2)		(3)
Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	2,037		3,390
Interest rate swaps assets	15		3
Foreign currency contracts assets			18
Cross-currency swaps assets	13		20
Total price risk management assets	2,065		3,431
NDT funds	275		256
Auction rate securities	3	[2]
Total assets	2,343		3,687
Price risk management liabilities:
Energy commodities liabilities	1,557		2,327
Interest rate swaps liabilities	80		63
Foreign currency contracts liabilities	44
Cross-currency swaps liabilities	4		2
Total price risk management liabilities	1,685		2,392
Level 2 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds
Level 2 [Member] | US Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	104		90
Level 2 [Member] | US Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	35		30
Level 2 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds
Level 2 [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		10
Level 2 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	82		83
Level 2 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	40		38
Level 2 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		2
Level 2 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	2		3
Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	29		30
Interest rate swaps assets
Foreign currency contracts assets
Cross-currency swaps assets	1		4
Total price risk management assets	30		34
NDT funds
Auction rate securities	16	[2]	24	[2]
Total assets	46		58
Price risk management liabilities:
Energy commodities liabilities	7		17
Interest rate swaps liabilities
Foreign currency contracts liabilities
Cross-currency swaps liabilities
Total price risk management liabilities	7		17
Level 3 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | US Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | US Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds
Level 3 [Member] | US 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	413		379
Restricted cash and cash equivalents	63	[1]	145	[1]
Price risk management assets:
Energy commodities assets	2,068		3,423
Total price risk management assets	2,068		3,423
NDT funds	712		640
Auction rate securities	16	[2]	19	[2]
Total assets	3,272		4,606
Price risk management liabilities:
Energy commodities liabilities	1,566		2,345
Total price risk management liabilities	1,566		2,345
PPL Energy Supply LLC [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	11		12
PPL Energy Supply LLC [Member] | US Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	412		357
PPL Energy Supply LLC [Member] | US Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	60		52
PPL Energy Supply LLC [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	95		86
PPL Energy Supply LLC [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		10
PPL Energy Supply LLC [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	82		83
PPL Energy Supply LLC [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	40		38
PPL Energy Supply LLC [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		2
PPL Energy Supply LLC [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	413		379
Restricted cash and cash equivalents	63	[1]	145	[1]
Price risk management assets:
Energy commodities assets	2		3
Total price risk management assets	2		3
NDT funds	437		384
Auction rate securities
Total assets	915		911
Price risk management liabilities:
Energy commodities liabilities	2		1
Total price risk management liabilities	2		1
PPL Energy Supply LLC [Member] | Level 1 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	11		12
PPL Energy Supply LLC [Member] | Level 1 [Member] | US Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	308		267
PPL Energy Supply LLC [Member] | Level 1 [Member] | US Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	25		22
PPL Energy Supply LLC [Member] | Level 1 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	95		86
PPL Energy Supply LLC [Member] | Level 1 [Member] | US 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	(2)		(3)
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	2,037		3,390
Total price risk management assets	2,037		3,390
NDT funds	275		256
Auction rate securities	3	[2]
Total assets	2,315		3,646
Price risk management liabilities:
Energy commodities liabilities	1,557		2,327
Total price risk management liabilities	1,557		2,327
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] | US Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	104		90
PPL Energy Supply LLC [Member] | Level 2 [Member] | US Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	35		30
PPL Energy Supply LLC [Member] | Level 2 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 2 [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		10
PPL Energy Supply LLC [Member] | Level 2 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	82		83
PPL Energy Supply LLC [Member] | Level 2 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	40		38
PPL Energy Supply LLC [Member] | Level 2 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		2
PPL Energy Supply LLC [Member] | Level 2 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	2		3
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	29		30
Total price risk management assets	29		30
NDT funds
Auction rate securities	13	[2]	19	[2]
Total assets	42		49
Price risk management liabilities:
Energy commodities liabilities	7		17
Total price risk management liabilities	7		17
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] | US Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | US Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds
PPL Energy Supply LLC [Member] | Level 3 [Member] | US 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	140		320
Restricted cash and cash equivalents	13	[3]	13	[3]
Price risk management assets:
Total assets	153		333
PPL Electric Utilities Corp [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	140		320
Restricted cash and cash equivalents	13	[3]	13	[3]
Price risk management assets:
Total assets	153		333
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	43		59
Restricted cash and cash equivalents	32	[4]	29	[4]
Price risk management assets:
Interest rate swaps assets	14
Total price risk management assets	14
Total assets	89		88
Price risk management liabilities:
Interest rate swaps liabilities	58	[5]	60	[5]
Total price risk management liabilities	58		60
LG And E And KU Energy LLC [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	43		59
Restricted cash and cash equivalents	32	[4]	29	[4]
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets	75		88
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	14
Total price risk management assets	14
Total assets	14
Price risk management liabilities:
Interest rate swaps liabilities	58	[5]	60	[5]
Total price risk management liabilities	58		60
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	22		25
Restricted cash and cash equivalents	32	[4]	29	[4]
Price risk management assets:
Interest rate swaps assets	7
Total price risk management assets	7
Total assets	61		54
Price risk management liabilities:
Interest rate swaps liabilities	58	[5]	60	[5]
Total price risk management liabilities	58		60
Louisville Gas And Electric Co [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	22		25
Restricted cash and cash equivalents	32	[4]	29	[4]
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets	54		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	7
Total price risk management assets	7
Total assets	7
Price risk management liabilities:
Interest rate swaps liabilities	58	[5]	60	[5]
Total price risk management liabilities	58		60
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	21		31
Price risk management assets:
Interest rate swaps assets	7
Total price risk management assets	7
Total assets	28		31
Kentucky Utilities Co [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	21		31
Price risk management assets:
Interest rate swaps assets
Total price risk management assets
Total assets	21		31
Kentucky Utilities Co [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Price risk management assets:
Interest rate swaps assets	7
Total price risk management assets	7
Total assets	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 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.

[5] Current portion is included in "Other current liabilities" on the Balance Sheets.  The long-term portion is included in "Price risk management liabilities" on the Balance Sheets.