Fair Value Measurements and Credit Concentration (Assets and Liabilities Measured on Recurring Basis Table) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 946		$ 1,202		$ 1,511	$ 925
Debt securities:
Total NDT funds	711		640
Recurring [Member]
Assets
Cash and cash equivalents	946		1,202
Restricted cash and cash equivalents	169	[1]	209	[1]
Price risk management assets:
Energy commodities assets	2,604		3,423
Interest rate swaps assets			3
Foreign currency contracts assets			18
Cross-currency swaps assets	24		24
Total price risk management assets	2,628		3,468
NDT funds:
Cash and cash equivalents	12		12
Equity Securities (Numeric) [Abstract]
U.S. large-cap	412		357
U.S. mid/small-cap	59		52
Debt securities:
U.S. Treasury	95		86
U.S. government sponsored agency	9		10
Municipality	83		83
Investment-grade corporate	40		38
Other	2		2
Receivables (payables), net	(1)
Total NDT funds	711		640
Auction rate securities	19	[2]	24	[2]
Total assets	4,473		5,543
Price risk management liabilities:
Energy commodities liabilities	1,947		2,345
Interest rate swaps liabilities	83		63
Foreign currency contracts liabilities	36
Cross-currency swaps liabilities	2		2
Total price risk management liabilities	2,068		2,410
Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	946		1,202
Restricted cash and cash equivalents	169	[1]	209	[1]
Price risk management assets:
Energy commodities assets	5		3
Interest rate swaps assets
Foreign currency contracts assets
Cross-currency swaps assets
Total price risk management assets	5		3
NDT funds:
Cash and cash equivalents	12		12
Equity Securities (Numeric) [Abstract]
U.S. large-cap	307		267
U.S. mid/small-cap	25		22
Debt securities:
U.S. Treasury	95		86
U.S. government sponsored agency
Municipality
Investment-grade corporate
Other
Receivables (payables), net	(3)		(3)
Total NDT funds	436		384
Auction rate securities
Total assets	1,556		1,798
Price risk management liabilities:
Energy commodities liabilities	5		1
Interest rate swaps liabilities
Foreign currency contracts liabilities
Cross-currency swaps liabilities
Total price risk management liabilities	5		1
Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	2,569		3,390
Interest rate swaps assets			3
Foreign currency contracts assets			18
Cross-currency swaps assets	22		20
Total price risk management assets	2,591		3,431
NDT funds:
Cash and cash equivalents
Equity Securities (Numeric) [Abstract]
U.S. large-cap	105		90
U.S. mid/small-cap	34		30
Debt securities:
U.S. Treasury
U.S. government sponsored agency	9		10
Municipality	83		83
Investment-grade corporate	40		38
Other	2		2
Receivables (payables), net	2		3
Total NDT funds	275		256
Auction rate securities	3	[2]
Total assets	2,869		3,687
Price risk management liabilities:
Energy commodities liabilities	1,937		2,327
Interest rate swaps liabilities	83		63
Foreign currency contracts liabilities	36
Cross-currency swaps liabilities	2		2
Total price risk management liabilities	2,058		2,392
Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	30		30
Interest rate swaps assets
Foreign currency contracts assets
Cross-currency swaps assets	2		4
Total price risk management assets	32		34
NDT funds:
Cash and cash equivalents
Equity Securities (Numeric) [Abstract]
U.S. large-cap
U.S. mid/small-cap
Debt securities:
U.S. Treasury
U.S. government sponsored agency
Municipality
Investment-grade corporate
Other
Receivables (payables), net
Total NDT funds
Auction rate securities	16	[2]	24
Total assets	48		58
Price risk management liabilities:
Energy commodities liabilities	5		17
Interest rate swaps liabilities
Foreign currency contracts liabilities
Cross-currency swaps liabilities
Total price risk management liabilities	5		17
PPL Energy Supply LLC [Member]
Assets
Cash and cash equivalents	432		379		375	661
Debt securities:
Total NDT funds	711		640
PPL Energy Supply LLC [Member] | Recurring [Member]
Assets
Cash and cash equivalents	432		379
Restricted cash and cash equivalents	98	[1]	145	[1]
Price risk management assets:
Energy commodities assets	2,604		3,423
Total price risk management assets	2,604		3,423
NDT funds:
Cash and cash equivalents	12		12
Equity Securities (Numeric) [Abstract]
U.S. large-cap	412		357
U.S. mid/small-cap	59		52
Debt securities:
U.S. Treasury	95		86
U.S. government sponsored agency	9		10
Municipality	83		83
Investment-grade corporate	40		38
Other	2		2
Receivables (payables), net	(1)
Total NDT funds	711		640
Auction rate securities	16	[2]	19	[2]
Total assets	3,861		4,606
Price risk management liabilities:
Energy commodities liabilities	1,947		2,345
Total price risk management liabilities	1,947		2,345
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	432		379
Restricted cash and cash equivalents	98	[1]	145	[1]
Price risk management assets:
Energy commodities assets	5		3
Total price risk management assets	5		3
NDT funds:
Cash and cash equivalents	12		12
Equity Securities (Numeric) [Abstract]
U.S. large-cap	307		267
U.S. mid/small-cap	25		22
Debt securities:
U.S. Treasury	95		86
U.S. government sponsored agency
Municipality
Investment-grade corporate
Other
Receivables (payables), net	(3)		(3)
Total NDT funds	436		384
Auction rate securities
Total assets	971		911
Price risk management liabilities:
Energy commodities liabilities	5		1
Total price risk management liabilities	5		1
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	2,569		3,390
Total price risk management assets	2,569		3,390
NDT funds:
Cash and cash equivalents
Equity Securities (Numeric) [Abstract]
U.S. large-cap	105		90
U.S. mid/small-cap	34		30
Debt securities:
U.S. Treasury
U.S. government sponsored agency	9		10
Municipality	83		83
Investment-grade corporate	40		38
Other	2		2
Receivables (payables), net	2		3
Total NDT funds	275		256
Auction rate securities	3	[2]
Total assets	2,847		3,646
Price risk management liabilities:
Energy commodities liabilities	1,937		2,327
Total price risk management liabilities	1,937		2,327
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Price risk management assets:
Energy commodities assets	30		30
Total price risk management assets	30		30
NDT funds:
Cash and cash equivalents
Equity Securities (Numeric) [Abstract]
U.S. large-cap
U.S. mid/small-cap
Debt securities:
U.S. Treasury
U.S. government sponsored agency
Municipality
Investment-grade corporate
Other
Receivables (payables), net
Total NDT funds
Auction rate securities	13	[2]	19	[2]
Total assets	43		49
Price risk management liabilities:
Energy commodities liabilities	5		17
Total price risk management liabilities	5		17
PPL Electric Utilities Corp [Member]
Assets
Cash and cash equivalents	31		320		261	204
PPL Electric Utilities Corp [Member] | Recurring [Member]
Assets
Cash and cash equivalents	31		320
Restricted cash and cash equivalents	13	[3]	13	[3]
Debt securities:
Total assets	44		333
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	31		320
Restricted cash and cash equivalents	13	[3]	13
Debt securities:
Total assets	44		333
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Debt securities:
Total assets
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Debt securities:
Total assets
LG And E And KU Energy LLC [Member]
Assets
Cash and cash equivalents	90		59		170	11
LG And E And KU Energy LLC [Member] | Recurring [Member]
Assets
Cash and cash equivalents	90		59
Restricted cash and cash equivalents	32	[4]	29	[4]
Debt securities:
Total assets	122		88
Price risk management liabilities:
Interest rate swaps liabilities	62	[5]	60	[5]
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	90		59
Restricted cash and cash equivalents	32	[4]	29	[4]
Debt securities:
Total assets	122		88
Price risk management liabilities:
Interest rate swaps liabilities
Total price risk management liabilities
LG And E And KU Energy LLC [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Debt securities:
Total assets
Price risk management liabilities:
Interest rate swaps liabilities	62	[5]	60	[5]
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
Restricted cash and cash equivalents
Debt securities:
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	48		25		75	2
Louisville Gas And Electric Co [Member] | Recurring [Member]
Assets
Cash and cash equivalents	48		25
Restricted cash and cash equivalents	32	[4]	29	[4]
Debt securities:
Total assets	80		54
Price risk management liabilities:
Interest rate swaps liabilities	62	[5]	60	[5]
Total price risk management liabilities	62		60
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	48		25
Restricted cash and cash equivalents	32	[4]	29	[4]
Debt securities:
Total assets	80		54
Price risk management liabilities:
Interest rate swaps liabilities
Total price risk management liabilities
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Debt securities:
Total assets
Price risk management liabilities:
Interest rate swaps liabilities	62	[5]	60	[5]
Total price risk management liabilities	62		60
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Restricted cash and cash equivalents
Debt securities:
Total assets
Price risk management liabilities:
Interest rate swaps liabilities
Total price risk management liabilities
Kentucky Utilities Co [Member]
Assets
Cash and cash equivalents	42		31		94	3
Kentucky Utilities Co [Member] | Recurring [Member]
Assets
Cash and cash equivalents	42		31
Debt securities:
Total assets	42		31
Kentucky Utilities Co [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	42		31
Debt securities:
Total assets	42		31
Kentucky Utilities Co [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents
Debt securities:
Total assets
Kentucky Utilities Co [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents
Debt securities:
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.

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