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, 2014		Dec. 31, 2013
Reconciliation of net assets and liabilities
Balance at beginning of period	$ 43		$ 39
Total realized/unrealized gains (losses)
Included in earnings	(32)		(5)
Included in OCI	(2)	[1]	1	[1]
Purchases	(6)
Sales	58		(2)
Settlements	50		(3)
Transfers into Level 3	8		16
Transfers out of Level 3	3		(3)
Balance at end of period	122		43
Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	24		22
Total realized/unrealized gains (losses)
Included in earnings	(32)		(5)
Included in OCI	0		0
Purchases	(6)
Sales	67		(2)
Settlements	50		(3)
Transfers into Level 3	7		10
Transfers out of Level 3	1		2
Balance at end of period	111		24
Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	19		16
Total realized/unrealized gains (losses)
Included in earnings	0		0
Included in OCI	0		0
Purchases	0
Sales	(9)		0
Settlements	0		0
Transfers into Level 3	0		3
Transfers out of Level 3	0		0
Balance at end of period	10		19
Cross Currency Swaps [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	0		1
Total realized/unrealized gains (losses)
Included in earnings	0		0
Included in OCI	(2)	[1]	1	[1]
Purchases	0
Sales	0		0
Settlements	0		0
Transfers into Level 3	1		3
Transfers out of Level 3	2		(5)
Balance at end of period	1		0
PPL Energy Supply LLC [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	40		35
Total realized/unrealized gains (losses)
Included in earnings	(32)		(5)
Included in OCI	1	[2]
Purchases	(6)
Sales	58		(2)
Settlements	50		(3)
Transfers into Level 3	7		13
Transfers out of Level 3	1		2
Balance at end of period	119		40
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	24		22
Total realized/unrealized gains (losses)
Included in earnings	(32)		(5)
Included in OCI	0
Purchases	(6)
Sales	67		(2)
Settlements	50		(3)
Transfers into Level 3	7		10
Transfers out of Level 3	1		2
Balance at end of period	111		24
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	16		13
Total realized/unrealized gains (losses)
Included in earnings	0		0
Included in OCI	1	[2]
Purchases	0
Sales	(9)		0
Settlements	0		0
Transfers into Level 3	0		3
Transfers out of Level 3	0		0
Balance at end of period	$ 8		$ 16

[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.