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	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Reconciliation of net assets and liabilities
Balance at beginning of period	$ 41		$ 22
Total realized/unrealized gains (losses)
Included in earnings	1		(65)
Included in OCI	2	[1]	(12)	[1]
Purchases			1
Sales	(5)		(3)
Settlements	(13)		20
Transfers into Level 3	8		4
Transfers out of Level 3	5		74
Balance at end of period	39		41
Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	13		(3)
Total realized/unrealized gains (losses)
Included in earnings	2		(65)
Included in OCI	1	[1]	(1)	[1]
Purchases			1
Sales			(3)
Settlements	(13)		20
Transfers into Level 3	8		(10)
Transfers out of Level 3	11		74
Balance at end of period	22		13
Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	24		25
Total realized/unrealized gains (losses)
Included in earnings
Included in OCI			(1)	[1]
Purchases
Sales	(5)
Settlements
Transfers into Level 3
Transfers out of Level 3	(3)
Balance at end of period	16		24
Cross Currency Swaps [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	4
Total realized/unrealized gains (losses)
Included in earnings	(1)
Included in OCI	1	[1]	(10)	[1]
Purchases
Sales
Settlements
Transfers into Level 3			14
Transfers out of Level 3	(3)
Balance at end of period	1		4
PPL Energy Supply LLC [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	32		17
Total realized/unrealized gains (losses)
Included in earnings	2		(65)
Included in OCI	1	[2]	(2)	[2]
Purchases			1
Sales	(3)		(3)
Settlements	(13)		20
Transfers into Level 3	8		(10)
Transfers out of Level 3	8		74
Balance at end of period	35		32
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	13		(3)
Total realized/unrealized gains (losses)
Included in earnings	2		(65)
Included in OCI	1	[2]	(1)	[2]
Purchases			1
Sales			(3)
Settlements	(13)		20
Transfers into Level 3	8		(10)
Transfers out of Level 3	11		74
Balance at end of period	22		13
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	19		20
Total realized/unrealized gains (losses)
Included in earnings
Included in OCI			(1)	[2]
Purchases
Sales	(3)
Settlements
Transfers into Level 3
Transfers out of Level 3	(3)
Balance at end of period	$ 13		$ 19

[1] "Energy Commodities" 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] At December 31, 2012 and December 31, 2011, includes $428 million and $416 million of PP&E, consisting primarily of "Generation," including leasehold improvements, and $10 million and $11 million of "Other intangibles" from the consolidation of a VIE that is the owner/lessor of the Lower Mt. Bethel plant. See Note 22 for additional information.