Fair Value Measurements and Credit Concentration (Net Asset and Liability Measured on Recurring Basis Level 3 Observable Input Reconciliation Rollforward) (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Reconciliation of net assets and liabilities
Balance at beginning of period	$ 46		$ 57		$ 41		$ 22
Total realized/unrealized gains (losses)
Included in earnings	(3)		(5)		15		(4)
Included in OCI	6	[1]	3	[2]	10	[1]	4	[2]
Purchases	0		0		0		2
Sales	(5)		(1)		(5)		(4)
Settlements	(5)		3		(11)		25
Transfers into Level 3	14				14
Transfers out of Level 3	6		(6)		(5)		6
Balance at end of period	59		51		59		51
Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	19		32		13		(3)
Total realized/unrealized gains (losses)
Included in earnings	(2)		(5)		16		(4)
Included in OCI	(1)	[1]	3	[2]	1	[1]	4	[2]
Purchases	0		0		0		2
Sales	0		(1)		0		(4)
Settlements	(5)		3		(11)		25
Transfers into Level 3	14				14
Transfers out of Level 3	9		(6)		1		6
Balance at end of period	34		26		34		26
Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	24		25		24		25
Total realized/unrealized gains (losses)
Included in earnings	0		0		0		0
Included in OCI	(1)	[1]	0		(1)	[1]	0
Purchases	0		0		0		0
Sales	(5)		0		(5)		0
Settlements	0		0		0		0
Transfers into Level 3	0				0
Transfers out of Level 3	(3)		0		(3)		0
Balance at end of period	15		25		15		25
Cross Currency Swaps [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	3				4
Total realized/unrealized gains (losses)
Included in earnings	(1)				(1)
Included in OCI	8	[1]			10	[1]
Purchases	0				0
Sales	0				0
Settlements	0				0
Transfers into Level 3	0				0
Transfers out of Level 3	0				(3)
Balance at end of period	10				10
PPL Energy Supply LLC [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	38		52		32		17
Total realized/unrealized gains (losses)
Included in earnings	(2)		(5)		16		(4)
Included in OCI	(2)	[1]	3	[2]	0	[1]	4	[2]
Purchases	0		0		0		2
Sales	(3)		(1)		(3)		(4)
Settlements	(5)		3		(11)		25
Transfers into Level 3	14				14
Transfers out of Level 3	6		(6)		(2)		6
Balance at end of period	46		46		46		46
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	19		32		13		(3)
Total realized/unrealized gains (losses)
Included in earnings	(2)		(5)		16		(4)
Included in OCI	(1)	[1]	3	[2]	1	[1]	4	[2]
Purchases	0		0		0		2
Sales	0		(1)		0		(4)
Settlements	(5)		3		(11)		25
Transfers into Level 3	14				14
Transfers out of Level 3	9		(6)		1		6
Balance at end of period	34		26		34		26
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	19		20		19		20
Total realized/unrealized gains (losses)
Included in earnings	0		0		0		0
Included in OCI	(1)	[1]	0		(1)	[1]	0
Purchases	0		0		0		0
Sales	(3)		0		(3)		0
Settlements	0		0		0		0
Transfers into Level 3	0				0
Transfers out of Level 3	(3)		0		(3)		0
Balance at end of period	$ 12		$ 20		$ 12		$ 20

[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.