Fair Value Measurements and Credit Concentration (Assets and Liabilities Measured on Recurring Basis Table) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Price risk management liabilities:
Total price risk management liabilities	$ 1,378		$ 1,244
Recurring [Member]
Assets
Cash and cash equivalents	1,751		1,102
Short-term investments	120		0
Restricted cash and cash equivalents	224	[1]	134	[1]
Price risk management assets:
Energy commodities assets	1,318		1,188
Interest rate swaps assets	0		91
Foreign currency contracts assets	130		0
Cross-currency swaps assets	29		0
Total price risk management assets	1,477		1,279
NDT funds	950		864
Auction rate securities	10	[2]	19	[2]
Total assets	4,532		3,398
Price risk management liabilities:
Energy commodities liabilities	1,217		1,070
Interest rate swaps liabilities	156		36
Foreign currency contracts liabilities	2		106
Cross-currency swaps liabilities	3		32
Total price risk management liabilities	1,378		1,244
Recurring [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	19		14
Recurring [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	611		547
Recurring [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	89		81
Recurring [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	99		95
Recurring [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		6
Recurring [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	76		77
Recurring [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	42		38
Recurring [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		5
Recurring [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	2		1
Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	1,751		1,102
Short-term investments	120		0
Restricted cash and cash equivalents	224	[1]	134	[1]
Price risk management assets:
Energy commodities assets	6		3
Interest rate swaps assets	0		0
Foreign currency contracts assets	0		0
Cross-currency swaps assets	0		0
Total price risk management assets	6		3
NDT funds	609		550
Auction rate securities	0		0
Total assets	2,710		1,789
Price risk management liabilities:
Energy commodities liabilities	5		4
Interest rate swaps liabilities	0		0
Foreign currency contracts liabilities	0		0
Cross-currency swaps liabilities	0		0
Total price risk management liabilities	5		4
Recurring [Member] | Level 1 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	19		14
Recurring [Member] | Level 1 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	454		409
Recurring [Member] | Level 1 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	37		33
Recurring [Member] | Level 1 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	99		95
Recurring [Member] | Level 1 [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 1 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 1 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 1 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 1 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	0		(1)
Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Short-term investments	0		0
Restricted cash and cash equivalents	0		0
Price risk management assets:
Energy commodities assets	1,171		1,123
Interest rate swaps assets	0		91
Foreign currency contracts assets	130		0
Cross-currency swaps assets	28		0
Total price risk management assets	1,329		1,214
NDT funds	341		314
Auction rate securities	0		0
Total assets	1,670		1,528
Price risk management liabilities:
Energy commodities liabilities	1,182		1,028
Interest rate swaps liabilities	156		36
Foreign currency contracts liabilities	2		106
Cross-currency swaps liabilities	3		32
Total price risk management liabilities	1,343		1,202
Recurring [Member] | Level 2 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 2 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	157		138
Recurring [Member] | Level 2 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	52		48
Recurring [Member] | Level 2 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 2 [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		6
Recurring [Member] | Level 2 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	76		77
Recurring [Member] | Level 2 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	42		38
Recurring [Member] | Level 2 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		5
Recurring [Member] | Level 2 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	2		2
Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Short-term investments	0		0
Restricted cash and cash equivalents	0		0
Price risk management assets:
Energy commodities assets	141		62
Interest rate swaps assets	0		0
Foreign currency contracts assets	0		0
Cross-currency swaps assets	1		0
Total price risk management assets	142		62
NDT funds	0		0
Auction rate securities	10	[2]	19	[2]
Total assets	152		81
Price risk management liabilities:
Energy commodities liabilities	30		38
Interest rate swaps liabilities	0		0
Foreign currency contracts liabilities	0		0
Cross-currency swaps liabilities	0		0
Total price risk management liabilities	30		38
Recurring [Member] | Level 3 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member]
Assets
Cash and cash equivalents	352		239
Restricted cash and cash equivalents	193	[1]	85	[1]
Price risk management assets:
Energy commodities assets	1,318		1,188
Total price risk management assets	1,318		1,188
NDT funds	950		864
Auction rate securities	8	[2]	16	[2]
Total assets	2,821		2,392
Price risk management liabilities:
Energy commodities liabilities	1,217		1,070
Total price risk management liabilities	1,217		1,070
PPL Energy Supply LLC [Member] | Recurring [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	19		14
PPL Energy Supply LLC [Member] | Recurring [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	611		547
PPL Energy Supply LLC [Member] | Recurring [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	89		81
PPL Energy Supply LLC [Member] | Recurring [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	99		95
PPL Energy Supply LLC [Member] | Recurring [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		6
PPL Energy Supply LLC [Member] | Recurring [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	76		77
PPL Energy Supply LLC [Member] | Recurring [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	42		38
PPL Energy Supply LLC [Member] | Recurring [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		5
PPL Energy Supply LLC [Member] | Recurring [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	2		1
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	352		239
Restricted cash and cash equivalents	193	[1]	85	[1]
Price risk management assets:
Energy commodities assets	6		3
Total price risk management assets	6		3
NDT funds	609		550
Auction rate securities	0		0
Total assets	1,160		877
Price risk management liabilities:
Energy commodities liabilities	5		4
Total price risk management liabilities	5		4
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	19		14
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	454		409
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	37		33
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	99		95
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 1 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	0		(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	1,171		1,123
Total price risk management assets	1,171		1,123
NDT funds	341		314
Auction rate securities	0		0
Total assets	1,512		1,437
Price risk management liabilities:
Energy commodities liabilities	1,182		1,028
Total price risk management liabilities	1,182		1,028
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	157		138
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	52		48
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	9		6
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	76		77
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	42		38
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		5
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 2 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	2		2
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	141		62
Total price risk management assets	141		62
NDT funds	0		0
Auction rate securities	8	[2]	16	[2]
Total assets	149		78
Price risk management liabilities:
Energy commodities liabilities	30		38
Total price risk management liabilities	30		38
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | US Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | US Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
PPL Energy Supply LLC [Member] | Recurring [Member] | Level 3 [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	0		0
PPL Electric Utilities Corp [Member] | Recurring [Member]
Assets
Cash and cash equivalents	214		25
Restricted cash and cash equivalents	3	[3]	12	[3]
Price risk management assets:
Total assets	217		37
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	214		25
Restricted cash and cash equivalents	3	[3]	12	[3]
Price risk management assets:
Total assets	217		37
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Restricted cash and cash equivalents	0		0
Price risk management assets:
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
Price risk management assets:
Total assets	0		0
LG And E And KU Energy LLC [Member] | Recurring [Member]
Assets
Cash and cash equivalents	21		35
Price risk management assets:
Cash collateral posted to counterparties	21	[4]	22	[4]
Total assets	42		57
Price risk management liabilities:
Interest rate swaps liabilities	114		36
Total price risk management liabilities	114		36
LG And E And KU Energy LLC [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	21		35
Price risk management assets:
Cash collateral posted to counterparties	21	[4]	22	[4]
Total assets	42		57
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
Price risk management assets:
Cash collateral posted to counterparties	0		0
Total assets	0		0
Price risk management liabilities:
Interest rate swaps liabilities	114		36
Total price risk management liabilities	114		36
LG And E And KU Energy LLC [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Price risk management assets:
Cash collateral posted to counterparties	0		0
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] | Recurring [Member]
Assets
Cash and cash equivalents	10		8
Price risk management assets:
Cash collateral posted to counterparties	21	[4]	22	[4]
Total assets	31		30
Price risk management liabilities:
Interest rate swaps liabilities	81		36
Total price risk management liabilities	81		36
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	10		8
Price risk management assets:
Cash collateral posted to counterparties	21	[4]	22	[4]
Total assets	31		30
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
Price risk management assets:
Cash collateral posted to counterparties	0		0
Total assets	0		0
Price risk management liabilities:
Interest rate swaps liabilities	81		36
Total price risk management liabilities	81		36
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Price risk management assets:
Cash collateral posted to counterparties	0		0
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] | Recurring [Member]
Assets
Cash and cash equivalents	11		21
Price risk management assets:
Total assets	11		21
Price risk management liabilities:
Interest rate swaps liabilities	33		0
Total price risk management liabilities	33		0
Kentucky Utilities Co [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	11		21
Price risk management assets:
Total assets	11		21
Price risk management liabilities:
Interest rate swaps liabilities	0		0
Total price risk management liabilities	0		0
Kentucky Utilities Co [Member] | Recurring [Member] | Level 2 [Member]
Assets
Cash and cash equivalents	0		0
Price risk management assets:
Total assets	0		0
Price risk management liabilities:
Interest rate swaps liabilities	33		0
Total price risk management liabilities	33		0
Kentucky Utilities Co [Member] | Recurring [Member] | Level 3 [Member]
Assets
Cash and cash equivalents	0		0
Price risk management assets:
Total assets	0		0
Price risk management liabilities:
Interest rate swaps liabilities	0		0
Total price risk management liabilities	$ 0		$ 0

[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 long-term portion is included in "Other noncurrent assets" on the Balance Sheets.

[4] Included in "Other noncurrent assets" on the Balance Sheets. Represents cash collateral posted to offset the exposure with counterparties related to certain interest rate swaps under master netting arrangements that are not offset.