Fair Value Measurements and Credit Concentration (Net Asset and Liability Measured on Recurring Basis Level 3 Unobservable Inputs Reconciliation Rollforward) (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Reconciliation of net assets and liabilities
Balance at beginning of period	$ 59		$ 51		$ 41		$ 22
Total realized/unrealized gains (losses)
Included in earnings	(17)		6		(2)		2
Included in OCI	(7)	[1]	1	[2]	3	[1]	5	[2]
Purchases							2
Sales					(5)		(4)
Settlements	2		(2)		(9)		23
Transfers into Level 3	(2)		13		12		13
Transfers out of Level 3	8		(5)		3		1
Balance at end of period	43		64		43		64
Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	34		26		13		(3)
Total realized/unrealized gains (losses)
Included in earnings	(17)		6		(1)		2
Included in OCI			2	[2]	1	[1]	6	[2]
Purchases							2
Sales							(4)
Settlements	2		(2)		(9)		23
Transfers into Level 3	(2)		(1)		12		(1)
Transfers out of Level 3	8		(5)		9		1
Balance at end of period	25		26		25		26
Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	15		25		24		25
Total realized/unrealized gains (losses)
Included in earnings
Included in OCI	1	[1]	(1)	[2]			(1)	[2]
Purchases
Sales					(5)
Settlements
Transfers into Level 3
Transfers out of Level 3					(3)
Balance at end of period	16		24		16		24
Cross Currency Swaps [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	10				4
Total realized/unrealized gains (losses)
Included in earnings					(1)
Included in OCI	(8)	[1]			2	[1]
Purchases
Sales
Settlements
Transfers into Level 3			14				14
Transfers out of Level 3					(3)
Balance at end of period	2		14		2		14
PPL Energy Supply LLC [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	46		46		32		17
Total realized/unrealized gains (losses)
Included in earnings	(17)		6		(1)		2
Included in OCI	1	[1]	1	[2]	1	[1]	5	[2]
Purchases							2
Sales					(3)		(4)
Settlements	2		(2)		(9)		23
Transfers into Level 3	(2)		(1)		12		(1)
Transfers out of Level 3	8		(5)		6		1
Balance at end of period	38		45		38		45
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	34		26		13		(3)
Total realized/unrealized gains (losses)
Included in earnings	(17)		6		(1)		2
Included in OCI			2	[2]	1	[1]	6	[2]
Purchases							2
Sales							(4)
Settlements	2		(2)		(9)		23
Transfers into Level 3	(2)		(1)		12		(1)
Transfers out of Level 3	8		(5)		9		1
Balance at end of period	25		26		25		26
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	12		20		19		20
Total realized/unrealized gains (losses)
Included in earnings
Included in OCI	1	[1]	(1)	[2]			(1)	[2]
Purchases
Sales					(3)
Settlements
Transfers into Level 3
Transfers out of Level 3					(3)
Balance at end of period	$ 13		$ 19		$ 13		$ 19

[1] "Energy Commodities, net" and "Cross-Currency Swaps" are included in "Qualifying derivatives" and "Auction Rate Securities" are included in "Available-for-sale securities" on the Statements of Comprehensive Income.

[2] "Energy Commodities, net" are included in "Qualifying derivatives" and "Auction Rate Securities" are included in "Available-for-sale securities" on the Statements of Comprehensive Income.