Fair Value Measurements and Credit Concentration (Assets and Liabilities Measured on Recurring Basis Table) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Price risk management liabilities:
Total price risk management liabilities	$ 1,406		$ 1,378
Recurring [Member]
Assets
Cash and cash equivalents	1,335		1,751
Short-term investments	135		120
Restricted cash and cash equivalents	231	[1]	224	[1]
Price risk management assets:
Energy commodities assets	1,298		1,318
Foreign currency contracts assets	209		130
Cross-currency swaps assets	49		29
Total price risk management assets	1,556		1,477
NDT funds	965		950
Auction rate securities	10	[2]	10	[2]
Total assets	4,232		4,532
Price risk management liabilities:
Energy commodities liabilities	1,163		1,217
Interest rate swaps liabilities	235		156
Foreign currency contracts liabilities	6		2
Cross-currency swaps liabilities	2		3
Total price risk management liabilities	1,406		1,378
Recurring [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	20		19
Recurring [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	620		611
Recurring [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	93		89
Recurring [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	97		99
Recurring [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	8		9
Recurring [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	76		76
Recurring [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	45		42
Recurring [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		3
Recurring [Member] | Receivables Payables Net [Member]
Price risk management assets:
NDT funds	3		2
Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	1,335		1,751
Short-term investments	135		120
Restricted cash and cash equivalents	231	[1]	224	[1]
Price risk management assets:
Energy commodities assets	2		6
Foreign currency contracts assets	0		0
Cross-currency swaps assets	0		0
Total price risk management assets	2		6
NDT funds	617		609
Auction rate securities	0		0
Total assets	2,320		2,710
Price risk management liabilities:
Energy commodities liabilities	2		5
Interest rate swaps liabilities	0		0
Foreign currency contracts liabilities	0		0
Cross-currency swaps liabilities	0		0
Total price risk management liabilities	2		5
Recurring [Member] | Level 1 [Member] | Cash And Cash Equivalents [Member]
Price risk management assets:
NDT funds	20		19
Recurring [Member] | Level 1 [Member] | United States Large Cap Equity Securities [Member]
Price risk management assets:
NDT funds	461		454
Recurring [Member] | Level 1 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	38		37
Recurring [Member] | Level 1 [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	97		99
Recurring [Member] | Level 1 [Member] | United States 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	1		0
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	1,136		1,171
Foreign currency contracts assets	209		130
Cross-currency swaps assets	49		28
Total price risk management assets	1,394		1,329
NDT funds	348		341
Auction rate securities	0		0
Total assets	1,742		1,670
Price risk management liabilities:
Energy commodities liabilities	1,130		1,182
Interest rate swaps liabilities	235		156
Foreign currency contracts liabilities	6		2
Cross-currency swaps liabilities	2		3
Total price risk management liabilities	1,373		1,343
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	159		157
Recurring [Member] | Level 2 [Member] | United States Mid Small Cap Equity Securities [Member]
Price risk management assets:
NDT funds	55		52
Recurring [Member] | Level 2 [Member] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 2 [Member] | United States Government Sponsored Agency Debt Securities [Member]
Price risk management assets:
NDT funds	8		9
Recurring [Member] | Level 2 [Member] | Municipality Debt Securities [Member]
Price risk management assets:
NDT funds	76		76
Recurring [Member] | Level 2 [Member] | Investment Grade Corporate Debt Securities [Member]
Price risk management assets:
NDT funds	45		42
Recurring [Member] | Level 2 [Member] | Other Debt Securities [Member]
Price risk management assets:
NDT funds	3		3
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	160		141
Foreign currency contracts assets	0		0
Cross-currency swaps assets	0		1
Total price risk management assets	160		142
NDT funds	0		0
Auction rate securities	10	[2]	10	[2]
Total assets	170		152
Price risk management liabilities:
Energy commodities liabilities	31		30
Interest rate swaps liabilities	0		0
Foreign currency contracts liabilities	0		0
Cross-currency swaps liabilities	0		0
Total price risk management liabilities	31		30
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] | United States Treasury Debt Securities [Member]
Price risk management assets:
NDT funds	0		0
Recurring [Member] | Level 3 [Member] | United States 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 Electric Utilities Corp [Member] | Recurring [Member]
Assets
Cash and cash equivalents	35		214
Restricted cash and cash equivalents	2	[3]	3	[3]
Price risk management assets:
Total assets	37		217
PPL Electric Utilities Corp [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	35		214
Restricted cash and cash equivalents	2	[3]	3	[3]
Price risk management assets:
Total assets	37		217
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	40		21
Price risk management assets:
Cash collateral posted to counterparties	22	[4]	21	[4]
Total assets	62		42
Price risk management liabilities:
Interest rate swaps liabilities	174		114
Total price risk management liabilities	174		114
LG And E And KU Energy LLC [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	40		21
Price risk management assets:
Cash collateral posted to counterparties	22	[4]	21	[4]
Total assets	62		42
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	174		114
Total price risk management liabilities	174		114
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	17		10
Price risk management assets:
Cash collateral posted to counterparties	22	[4]	21	[4]
Total assets	39		31
Price risk management liabilities:
Interest rate swaps liabilities	113		81
Total price risk management liabilities	113		81
Louisville Gas And Electric Co [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	17		10
Price risk management assets:
Cash collateral posted to counterparties	22	[4]	21	[4]
Total assets	39		31
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	113		81
Total price risk management liabilities	113		81
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	23		11
Price risk management assets:
Total assets	23		11
Price risk management liabilities:
Interest rate swaps liabilities	61		33
Total price risk management liabilities	61		33
Kentucky Utilities Co [Member] | Recurring [Member] | Level 1 [Member]
Assets
Cash and cash equivalents	23		11
Price risk management assets:
Total assets	23		11
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	61		33
Total price risk management liabilities	61		33
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.