Fair Value Measurements and Credit Concentration (Assets and Liabilities Measured on Recurring Basis Table) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011		Jun. 30, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 981		$ 1,202		$ 1,269	$ 925
Debt securities:
Total NDT funds	681		640
Recurring [Member]
Assets
Cash and cash equivalents	981		1,202
Restricted cash and cash equivalents	176	[1]	209	[1]
Price risk management assets:
Energy commodities assets	3,506		3,423
Interest rate swaps assets	0		3
Foreign currency contracts assets	19		18
Cross-currency swaps assets	70		24
Total price risk management assets	3,595		3,468
NDT funds:
Cash and cash equivalents	14		12
Equity Securities (Numeric) [Abstract]
U.S. large-cap	317		292
U.S. mid/small-cap	127		117
Debt securities:
U.S. Treasury	96		86
U.S. government sponsored agency	10		10
Municipality	81		83
Investment-grade corporate	35		38
Other	2		2
Receivables (payables), net	(1)		0
Total NDT funds	681		640
Auction rate securities	18	[2]	24	[2]
Total assets	5,451		5,543
Price risk management liabilities:
Energy commodities liabilities	2,528		2,345
Interest rate swaps liabilities	77		63
Foreign currency contracts liabilities	4		0
Cross-currency swaps liabilities	2		2
Total price risk management liabilities	2,611		2,410
Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	981		1,202
Restricted cash and cash equivalents	176	[1]	209	[1]
Price risk management assets:
Energy commodities assets	3		3
Interest rate swaps assets	0		0
Foreign currency contracts assets	0		0
Cross-currency swaps assets	0		0
Total price risk management assets	3		3
NDT funds:
Cash and cash equivalents	14		12
Equity Securities (Numeric) [Abstract]
U.S. large-cap	219		202
U.S. mid/small-cap	94		87
Debt securities:
U.S. Treasury	96		86
U.S. government sponsored agency	0		0
Municipality	0		0
Investment-grade corporate	0		0
Other	0		0
Receivables (payables), net	(4)		(3)
Total NDT funds	419		384
Auction rate securities	0		0
Total assets	1,579		1,798
Price risk management liabilities:
Energy commodities liabilities	3		1
Interest rate swaps liabilities	0		0
Foreign currency contracts liabilities	0		0
Cross-currency swaps liabilities	0		0
Total price risk management liabilities	3		1
Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Price risk management assets:
Energy commodities assets	3,459		3,390
Interest rate swaps assets	0		3
Foreign currency contracts assets	19		18
Cross-currency swaps assets	60		20
Total price risk management assets	3,538		3,431
NDT funds:
Cash and cash equivalents	0		0
Equity Securities (Numeric) [Abstract]
U.S. large-cap	98		90
U.S. mid/small-cap	33		30
Debt securities:
U.S. Treasury	0		0
U.S. government sponsored agency	10		10
Municipality	81		83
Investment-grade corporate	35		38
Other	2		2
Receivables (payables), net	3		3
Total NDT funds	262		256
Auction rate securities	3		0
Total assets	3,803		3,687
Price risk management liabilities:
Energy commodities liabilities	2,515		2,327
Interest rate swaps liabilities	77		63
Foreign currency contracts liabilities	4		0
Cross-currency swaps liabilities	2		2
Total price risk management liabilities	2,598		2,392
Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Price risk management assets:
Energy commodities assets	44		30
Interest rate swaps assets	0		0
Foreign currency contracts assets	0		0
Cross-currency swaps assets	10		4
Total price risk management assets	54		34
NDT funds:
Cash and cash equivalents	0		0
Equity Securities (Numeric) [Abstract]
U.S. large-cap	0		0
U.S. mid/small-cap	0		0
Debt securities:
U.S. Treasury	0		0
U.S. government sponsored agency	0		0
Municipality	0		0
Investment-grade corporate	0		0
Other	0		0
Receivables (payables), net	0		0
Total NDT funds	0		0
Auction rate securities	15	[2]	24	[2]
Total assets	69		58
Price risk management liabilities:
Energy commodities liabilities	10		17
Interest rate swaps liabilities	0		0
Foreign currency contracts liabilities	0		0
Cross-currency swaps liabilities	0		0
Total price risk management liabilities	10		17
PPL Energy Supply LLC [Member]
Assets
Cash and cash equivalents	446		379		422	661
Debt securities:
Total NDT funds	681		640
PPL Energy Supply LLC [Member] | Recurring [Member]
Assets
Cash and cash equivalents	446		379
Restricted cash and cash equivalents	110	[1]	145	[1]
Price risk management assets:
Energy commodities assets	3,506		3,423
Total price risk management assets	3,506		3,423
NDT funds:
Cash and cash equivalents	14		12
Equity Securities (Numeric) [Abstract]
U.S. large-cap	317		292
U.S. mid/small-cap	127		117
Debt securities:
U.S. Treasury	96		86
U.S. government sponsored agency	10		10
Municipality	81		83
Investment-grade corporate	35		38
Other	2		2
Receivables (payables), net	(1)		0
Total NDT funds	681		640
Auction rate securities	15	[2]	19	[2]
Total assets	4,758		4,606
Price risk management liabilities:
Energy commodities liabilities	2,528		2,345
Total price risk management liabilities	2,528		2,345
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	446		379
Restricted cash and cash equivalents	110	[1]	145	[1]
Price risk management assets:
Energy commodities assets	3		3
Total price risk management assets	3		3
NDT funds:
Cash and cash equivalents	14		12
Equity Securities (Numeric) [Abstract]
U.S. large-cap	219		202
U.S. mid/small-cap	94		87
Debt securities:
U.S. Treasury	96		86
U.S. government sponsored agency	0		0
Municipality	0		0
Investment-grade corporate	0		0
Other	0		0
Receivables (payables), net	(4)		(3)
Total NDT funds	419		384
Auction rate securities	0		0
Total assets	978		911
Price risk management liabilities:
Energy commodities liabilities	3		1
Total price risk management liabilities	3		1
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Price risk management assets:
Energy commodities assets	3,459		3,390
Total price risk management assets	3,459		3,390
NDT funds:
Cash and cash equivalents	0		0
Equity Securities (Numeric) [Abstract]
U.S. large-cap	98		90
U.S. mid/small-cap	33		30
Debt securities:
U.S. Treasury	0		0
U.S. government sponsored agency	10		10
Municipality	81		83
Investment-grade corporate	35		38
Other	2		2
Receivables (payables), net	3		3
Total NDT funds	262		256
Auction rate securities	3		0
Total assets	3,724		3,646
Price risk management liabilities:
Energy commodities liabilities	2,515		2,327
Total price risk management liabilities	2,515		2,327
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Price risk management assets:
Energy commodities assets	44		30
Total price risk management assets	44		30
NDT funds:
Cash and cash equivalents	0		0
Equity Securities (Numeric) [Abstract]
U.S. large-cap	0		0
U.S. mid/small-cap	0		0
Debt securities:
U.S. Treasury	0		0
U.S. government sponsored agency	0		0
Municipality	0		0
Investment-grade corporate	0		0
Other	0		0
Receivables (payables), net	0		0
Total NDT funds	0		0
Auction rate securities	12	[2]	19	[2]
Total assets	56		49
Price risk management liabilities:
Energy commodities liabilities	10		17
Total price risk management liabilities	10		17
PPL Electric Utilities Corp [Member]
Assets
Cash and cash equivalents	45		320		4	204
PPL Electric Utilities Corp [Member] | Recurring [Member]
Assets
Cash and cash equivalents	45		320
Restricted cash and cash equivalents	13	[3]	13	[3]
Debt securities:
Total assets	58		333
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	45		320
Restricted cash and cash equivalents	13	[3]	13	[3]
Debt securities:
Total assets	58		333
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Debt securities:
Total assets	0		0
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Debt securities:
Total assets	0		0
LG And E And KU Energy LLC [Member]
Assets
Cash and cash equivalents	29		59		56	11
LG And E And KU Energy LLC [Member] | Recurring [Member]
Assets
Cash and cash equivalents	29		59
Restricted cash and cash equivalents	31	[3]	29	[3]
Debt securities:
Total assets	60		88
Price risk management liabilities:
Interest rate swaps liabilities	62	[4]	60	[4]
Total price risk management liabilities	62		60
LG And E And KU Energy LLC [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	29		59
Restricted cash and cash equivalents	31	[3]	29	[3]
Debt securities:
Total assets	60		88
Price risk management liabilities:
Interest rate swaps liabilities	0		0
Total price risk management liabilities	0		0
LG And E And KU Energy LLC [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Debt securities:
Total assets	0		0
Price risk management liabilities:
Interest rate swaps liabilities	62	[4]	60	[4]
Total price risk management liabilities	62		60
LG And E And KU Energy LLC [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Debt securities:
Total assets	0		0
Price risk management liabilities:
Interest rate swaps liabilities	0		0
Total price risk management liabilities	0		0
Louisville Gas And Electric Co [Member]
Assets
Cash and cash equivalents	25		25		41	2
Louisville Gas And Electric Co [Member] | Recurring [Member]
Assets
Cash and cash equivalents	25		25
Restricted cash and cash equivalents	31	[3]	29	[3]
Debt securities:
Total assets	56		54
Price risk management liabilities:
Interest rate swaps liabilities	62	[4]	60	[4]
Total price risk management liabilities	62		60
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	25		25
Restricted cash and cash equivalents	31	[3]	29	[3]
Debt securities:
Total assets	56		54
Price risk management liabilities:
Interest rate swaps liabilities	0		0
Total price risk management liabilities	0		0
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Debt securities:
Total assets	0		0
Price risk management liabilities:
Interest rate swaps liabilities	62	[4]	60	[4]
Total price risk management liabilities	62		60
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Debt securities:
Total assets	0		0
Price risk management liabilities:
Interest rate swaps liabilities	0		0
Total price risk management liabilities	0		0
Kentucky Utilities Co [Member]
Assets
Cash and cash equivalents	3		31		7	3
Kentucky Utilities Co [Member] | Recurring [Member]
Assets
Cash and cash equivalents	3		31
Debt securities:
Total assets	3		31
Kentucky Utilities Co [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	3		31
Debt securities:
Total assets	3		31
Kentucky Utilities Co [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Debt securities:
Total assets	0		0
Kentucky Utilities Co [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Debt securities:
Total assets	$ 0		$ 0

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